pgsql: Wording cleanup for error messages.

Log Message:
-----------
Wording cleanup for error messages.  Also change can't -> cannot.

Standard English uses "may", "can", and "might" in different ways:

        may - permission, "You may borrow my rake."

        can - ability, "I can lift that log."

        might - possibility, "It might rain today."

Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice.  Similarly, "It may crash" is better stated, "It might crash".

Modified Files:
--------------
    pgsql/contrib/spi:
        autoinc.c (r1.12 -> r1.13)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/spi/autoinc.c.diff?r1=1.12&r2=1.13)
        insert_username.c (r1.14 -> r1.15)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/spi/insert_username.c.diff?r1=1.14&r2=1.15)
        moddatetime.c (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/spi/moddatetime.c.diff?r1=1.13&r2=1.14)
        refint.c (r1.30 -> r1.31)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/spi/refint.c.diff?r1=1.30&r2=1.31)
        timetravel.c (r1.25 -> r1.26)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/spi/timetravel.c.diff?r1=1.25&r2=1.26)
    pgsql/contrib/tsearch2:
        dict_thesaurus.c (r1.7 -> r1.8)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/dict_thesaurus.c.diff?r1=1.7&r2=1.8)
        tsvector.c (r1.26 -> r1.27)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/tsvector.c.diff?r1=1.26&r2=1.27)
    pgsql/doc/src/sgml:
        ecpg.sgml (r1.79 -> r1.80)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ecpg.sgml.diff?r1=1.79&r2=1.80)
        gin.sgml (r2.9 -> r2.10)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/gin.sgml.diff?r1=2.9&r2=2.10)
        installation.sgml (r1.280 -> r1.281)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/installation.sgml.diff?r1=1.280&r2=1.281)
        lobj.sgml (r1.43 -> r1.44)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/lobj.sgml.diff?r1=1.43&r2=1.44)
        maintenance.sgml (r1.69 -> r1.70)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/maintenance.sgml.diff?r1=1.69&r2=1.70)
        perform.sgml (r1.62 -> r1.63)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/perform.sgml.diff?r1=1.62&r2=1.63)
        plperl.sgml (r2.62 -> r2.63)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/plperl.sgml.diff?r1=2.62&r2=2.63)
        queries.sgml (r1.43 -> r1.44)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/queries.sgml.diff?r1=1.43&r2=1.44)
        release.sgml (r1.495 -> r1.496)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release.sgml.diff?r1=1.495&r2=1.496)
        rules.sgml (r1.50 -> r1.51)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/rules.sgml.diff?r1=1.50&r2=1.51)
        sources.sgml (r2.23 -> r2.24)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/sources.sgml.diff?r1=2.23&r2=2.24)
        spi.sgml (r1.51 -> r1.52)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/spi.sgml.diff?r1=1.51&r2=1.52)
        sql.sgml (r1.44 -> r1.45)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/sql.sgml.diff?r1=1.44&r2=1.45)
        syntax.sgml (r1.113 -> r1.114)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/syntax.sgml.diff?r1=1.113&r2=1.114)
        typeconv.sgml (r1.50 -> r1.51)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/typeconv.sgml.diff?r1=1.50&r2=1.51)
        xfunc.sgml (r1.124 -> r1.125)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/xfunc.sgml.diff?r1=1.124&r2=1.125)
        xoper.sgml (r1.40 -> r1.41)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/xoper.sgml.diff?r1=1.40&r2=1.41)
    pgsql/doc/src/sgml/ref:
        create_function.sgml (r1.72 -> r1.73)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_function.sgml.diff?r1=1.72&r2=1.73)
        create_rule.sgml (r1.50 -> r1.51)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_rule.sgml.diff?r1=1.50&r2=1.51)
        create_trigger.sgml (r1.46 -> r1.47)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_trigger.sgml.diff?r1=1.46&r2=1.47)
        initdb.sgml (r1.39 -> r1.40)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/initdb.sgml.diff?r1=1.39&r2=1.40)
        notify.sgml (r1.29 -> r1.30)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/notify.sgml.diff?r1=1.29&r2=1.30)
        psql-ref.sgml (r1.182 -> r1.183)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/psql-ref.sgml.diff?r1=1.182&r2=1.183)
        rollback_to.sgml (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/rollback_to.sgml.diff?r1=1.8&r2=1.9)
        select.sgml (r1.98 -> r1.99)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/select.sgml.diff?r1=1.98&r2=1.99)
    pgsql/src/backend/access/gist:
        gistxlog.c (r1.25 -> r1.26)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistxlog.c.diff?r1=1.25&r2=1.26)
    pgsql/src/backend/access/hash:
        hashscan.c (r1.41 -> r1.42)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/hash/hashscan.c.diff?r1=1.41&r2=1.42)
    pgsql/src/backend/access/nbtree:
        nbtxlog.c (r1.40 -> r1.41)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/nbtree/nbtxlog.c.diff?r1=1.40&r2=1.41)
    pgsql/src/backend/access/transam:
        xact.c (r1.231 -> r1.232)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c.diff?r1=1.231&r2=1.232)
        xlog.c (r1.260 -> r1.261)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c.diff?r1=1.260&r2=1.261)
    pgsql/src/backend/catalog:
        aclchk.c (r1.135 -> r1.136)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/aclchk.c.diff?r1=1.135&r2=1.136)
        dependency.c (r1.62 -> r1.63)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/dependency.c.diff?r1=1.62&r2=1.63)
        index.c (r1.277 -> r1.278)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/index.c.diff?r1=1.277&r2=1.278)
        namespace.c (r1.90 -> r1.91)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/namespace.c.diff?r1=1.90&r2=1.91)
    pgsql/src/backend/commands:
        cluster.c (r1.155 -> r1.156)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/cluster.c.diff?r1=1.155&r2=1.156)
        comment.c (r1.95 -> r1.96)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/comment.c.diff?r1=1.95&r2=1.96)
        dbcommands.c (r1.190 -> r1.191)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/dbcommands.c.diff?r1=1.190&r2=1.191)
        indexcmds.c (r1.154 -> r1.155)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/indexcmds.c.diff?r1=1.154&r2=1.155)
        opclasscmds.c (r1.53 -> r1.54)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/opclasscmds.c.diff?r1=1.53&r2=1.54)
        portalcmds.c (r1.58 -> r1.59)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/portalcmds.c.diff?r1=1.58&r2=1.59)
        schemacmds.c (r1.42 -> r1.43)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/schemacmds.c.diff?r1=1.42&r2=1.43)
        sequence.c (r1.142 -> r1.143)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/sequence.c.diff?r1=1.142&r2=1.143)
        tablespace.c (r1.41 -> r1.42)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablespace.c.diff?r1=1.41&r2=1.42)
        user.c (r1.175 -> r1.176)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/user.c.diff?r1=1.175&r2=1.176)
        vacuum.c (r1.343 -> r1.344)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuum.c.diff?r1=1.343&r2=1.344)
    pgsql/src/backend/executor:
        execQual.c (r1.209 -> r1.210)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/execQual.c.diff?r1=1.209&r2=1.210)
    pgsql/src/backend/optimizer/plan:
        initsplan.c (r1.128 -> r1.129)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/initsplan.c.diff?r1=1.128&r2=1.129)
    pgsql/src/backend/optimizer/util:
        clauses.c (r1.231 -> r1.232)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/clauses.c.diff?r1=1.231&r2=1.232)
    pgsql/src/backend/parser:
        analyze.c (r1.359 -> r1.360)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/analyze.c.diff?r1=1.359&r2=1.360)
        gram.y (r2.577 -> r2.578)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y.diff?r1=2.577&r2=2.578)
        parse_agg.c (r1.76 -> r1.77)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_agg.c.diff?r1=1.76&r2=1.77)
        parse_clause.c (r1.163 -> r1.164)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_clause.c.diff?r1=1.163&r2=1.164)
        parse_func.c (r1.193 -> r1.194)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_func.c.diff?r1=1.193&r2=1.194)
        parse_oper.c (r1.93 -> r1.94)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_oper.c.diff?r1=1.93&r2=1.94)
    pgsql/src/backend/port/dynloader:
        aix.c (r1.18 -> r1.19)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/dynloader/aix.c.diff?r1=1.18&r2=1.19)
    pgsql/src/backend/regex:
        rege_dfa.c (r1.6 -> r1.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/regex/rege_dfa.c.diff?r1=1.6&r2=1.7)
    pgsql/src/backend/rewrite:
        rewriteDefine.c (r1.116 -> r1.117)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/rewrite/rewriteDefine.c.diff?r1=1.116&r2=1.117)
        rewriteHandler.c (r1.169 -> r1.170)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/rewrite/rewriteHandler.c.diff?r1=1.169&r2=1.170)
    pgsql/src/backend/storage/buffer:
        bufmgr.c (r1.214 -> r1.215)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/buffer/bufmgr.c.diff?r1=1.214&r2=1.215)
    pgsql/src/backend/storage/lmgr:
        lock.c (r1.175 -> r1.176)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lock.c.diff?r1=1.175&r2=1.176)
    pgsql/src/backend/utils/adt:
        genfile.c (r1.14 -> r1.15)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/genfile.c.diff?r1=1.14&r2=1.15)
        int.c (r1.77 -> r1.78)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/int.c.diff?r1=1.77&r2=1.78)
        int8.c (r1.63 -> r1.64)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/int8.c.diff?r1=1.63&r2=1.64)
    pgsql/src/backend/utils/fmgr:
        funcapi.c (r1.32 -> r1.33)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/fmgr/funcapi.c.diff?r1=1.32&r2=1.33)
    pgsql/src/backend/utils/init:
        miscinit.c (r1.160 -> r1.161)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/init/miscinit.c.diff?r1=1.160&r2=1.161)
    pgsql/src/backend/utils/misc:
        guc.c (r1.371 -> r1.372)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c.diff?r1=1.371&r2=1.372)
    pgsql/src/bin/initdb:
        initdb.c (r1.130 -> r1.131)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/initdb/initdb.c.diff?r1=1.130&r2=1.131)
    pgsql/src/bin/pg_ctl:
        pg_ctl.c (r1.76 -> r1.77)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_ctl/pg_ctl.c.diff?r1=1.76&r2=1.77)
    pgsql/src/bin/pg_dump:
        pg_backup_archiver.c (r1.140 -> r1.141)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_backup_archiver.c.diff?r1=1.140&r2=1.141)
    pgsql/src/bin/pg_resetxlog:
        pg_resetxlog.c (r1.55 -> r1.56)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_resetxlog/pg_resetxlog.c.diff?r1=1.55&r2=1.56)
    pgsql/src/bin/psql:
        startup.c (r1.139 -> r1.140)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/startup.c.diff?r1=1.139&r2=1.140)
    pgsql/src/include/regex:
        regerrs.h (r1.3 -> r1.4)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/regex/regerrs.h.diff?r1=1.3&r2=1.4)
    pgsql/src/interfaces/ecpg/preproc:
        ecpg.c (r1.96 -> r1.97)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/ecpg.c.diff?r1=1.96&r2=1.97)
        preproc.y (r1.339 -> r1.340)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/preproc.y.diff?r1=1.339&r2=1.340)
    pgsql/src/interfaces/libpq:
        win32.c (r1.21 -> r1.22)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/win32.c.diff?r1=1.21&r2=1.22)
    pgsql/src/pl/plperl:
        plperl.c (r1.125 -> r1.126)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c.diff?r1=1.125&r2=1.126)
    pgsql/src/pl/plpgsql/src:
        gram.y (r1.96 -> r1.97)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/gram.y.diff?r1=1.96&r2=1.97)
        pl_comp.c (r1.110 -> r1.111)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_comp.c.diff?r1=1.110&r2=1.111)
    pgsql/src/pl/plpython:
        plpython.c (r1.93 -> r1.94)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/plpython.c.diff?r1=1.93&r2=1.94)
    pgsql/src/pl/tcl:
        pltcl.c (r1.108 -> r1.109)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/tcl/pltcl.c.diff?r1=1.108&r2=1.109)
    pgsql/src/test/examples:
        testlo.c (r1.28 -> r1.29)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/examples/testlo.c.diff?r1=1.28&r2=1.29)
    pgsql/src/test/regress:
        pg_regress.c (r1.27 -> r1.28)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/pg_regress.c.diff?r1=1.27&r2=1.28)
        regress.c (r1.68 -> r1.69)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/regress.c.diff?r1=1.68&r2=1.69)
    pgsql/src/test/regress/expected:
        alter_table.out (r1.99 -> r1.100)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/alter_table.out.diff?r1=1.99&r2=1.100)
        create_view.out (r1.10 -> r1.11)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/create_view.out.diff?r1=1.10&r2=1.11)
        geometry.out (r1.24 -> r1.25)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/geometry.out.diff?r1=1.24&r2=1.25)
        horology.out (r1.64 -> r1.65)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/horology.out.diff?r1=1.64&r2=1.65)
        privileges.out (r1.35 -> r1.36)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/privileges.out.diff?r1=1.35&r2=1.36)
        rangefuncs.out (r1.15 -> r1.16)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/rangefuncs.out.diff?r1=1.15&r2=1.16)
        time.out (r1.12 -> r1.13)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/time.out.diff?r1=1.12&r2=1.13)
        timetz.out (r1.7 -> r1.8)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/timetz.out.diff?r1=1.7&r2=1.8)
        transactions.out (r1.14 -> r1.15)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/transactions.out.diff?r1=1.14&r2=1.15)
        triggers.out (r1.23 -> r1.24)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/triggers.out.diff?r1=1.23&r2=1.24)
    pgsql/src/test/thread:
        thread_test.c (r1.3 -> r1.4)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/thread/thread_test.c.diff?r1=1.3&r2=1.4)
    pgsql/src/timezone:
        zic.c (r1.20 -> r1.21)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/zic.c.diff?r1=1.20&r2=1.21)
    pgsql/src/tools/entab:
        entab.c (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tools/entab/entab.c.diff?r1=1.16&r2=1.17)