pgsql: Add RESET CONNECTION, to reset all aspects of a session.

Log Message:
-----------
Add RESET CONNECTION, to reset all aspects of a session.

Hans-J?rgen Sch?nig

Modified Files:
--------------
    pgsql/doc/src/sgml/ref:
        reset.sgml (r1.26 -> r1.27)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/reset.sgml.diff?r1=1.26&r2=1.27)
    pgsql/src/backend/catalog:
        namespace.c (r1.82 -> r1.83)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/namespace.c.diff?r1=1.82&r2=1.83)
    pgsql/src/backend/commands:
        async.c (r1.129 -> r1.130)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/async.c.diff?r1=1.129&r2=1.130)
        prepare.c (r1.50 -> r1.51)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/prepare.c.diff?r1=1.50&r2=1.51)
    pgsql/src/backend/parser:
        gram.y (r2.540 -> r2.541)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y.diff?r1=2.540&r2=2.541)
    pgsql/src/backend/utils/misc:
        guc.c (r1.315 -> r1.316)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c.diff?r1=1.315&r2=1.316)
    pgsql/src/backend/utils/mmgr:
        portalmem.c (r1.85 -> r1.86)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/mmgr/portalmem.c.diff?r1=1.85&r2=1.86)
    pgsql/src/include/catalog:
        namespace.h (r1.39 -> r1.40)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/namespace.h.diff?r1=1.39&r2=1.40)
    pgsql/src/include/commands:
        async.h (r1.31 -> r1.32)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/async.h.diff?r1=1.31&r2=1.32)
        prepare.h (r1.18 -> r1.19)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/prepare.h.diff?r1=1.18&r2=1.19)
    pgsql/src/include/utils:
        portal.h (r1.59 -> r1.60)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/portal.h.diff?r1=1.59&r2=1.60)
    pgsql/src/interfaces/ecpg/preproc:
        preproc.y (r1.321 -> r1.322)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/preproc.y.diff?r1=1.321&r2=1.322)