pgsql: Add psql \prompt capability.

Log Message:
-----------
Add psql \prompt capability.

Chad Wagner

Modified Files:
--------------
pgsql/doc/src/sgml/ref:
psql-ref.sgml (r1.186 -> r1.187)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/psql-ref.sgml.diff?r1=1.186&r2=1.187)
pgsql/src/bin/psql:
command.c (r1.177 -> r1.178)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/command.c.diff?r1=1.177&r2=1.178)
help.c (r1.116 -> r1.117)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/help.c.diff?r1=1.116&r2=1.117)
tab-complete.c (r1.158 -> r1.159)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/tab-complete.c.diff?r1=1.158&r2=1.159)