pgsql: Implement a psql command "\ef" to edit the definition of a

Log Message:
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Implement a psql command "\ef" to edit the definition of a function.
In support of that, create a backend function pg_get_functiondef().
The psql command is functional but maybe a bit rough around the edges...

Abhijit Menon-Sen

Modified Files:
--------------
    pgsql/doc/src/sgml:
        func.sgml (r1.443 -> r1.444)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.443&r2=1.444)
    pgsql/doc/src/sgml/ref:
        psql-ref.sgml (r1.209 -> r1.210)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/psql-ref.sgml?r1=1.209&r2=1.210)
    pgsql/src/backend/utils/adt:
        ruleutils.c (r1.282 -> r1.283)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/ruleutils.c?r1=1.282&r2=1.283)
    pgsql/src/bin/psql:
        command.c (r1.193 -> r1.194)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/command.c?r1=1.193&r2=1.194)
    pgsql/src/include/catalog:
        catversion.h (r1.482 -> r1.483)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.482&r2=1.483)
        pg_proc.h (r1.512 -> r1.513)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h?r1=1.512&r2=1.513)
    pgsql/src/include/utils:
        builtins.h (r1.319 -> r1.320)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h?r1=1.319&r2=1.320)