pgsql: Add regression tests for CSV and \., and add automatic quoting of

Log Message:
-----------
Add regression tests for CSV and \., and add automatic quoting of a
single column dump that has a \. value, so the load works properly.  I
also added documentation describing this issue.

Modified Files:
--------------
    pgsql/doc/src/sgml/ref:
        copy.sgml (r1.70 -> r1.71)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/copy.sgml.diff?r1=1.70&r2=1.71)
    pgsql/src/backend/commands:
        copy.c (r1.256 -> r1.257)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/copy.c.diff?r1=1.256&r2=1.257)
    pgsql/src/test/regress/expected:
        copy2.out (r1.22 -> r1.23)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/copy2.out.diff?r1=1.22&r2=1.23)
    pgsql/src/test/regress/sql:
        copy2.sql (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/copy2.sql.diff?r1=1.13&r2=1.14)