pgsql: Add timestamp and timestamptz versions of generate_series().

Log Message:
-----------
Add timestamp and timestamptz versions of generate_series().

Hitoshi Harada

Modified Files:
--------------
    pgsql/doc/src/sgml:
        func.sgml (r1.435 -> r1.436)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.435&r2=1.436)
    pgsql/src/backend/utils/adt:
        timestamp.c (r1.188 -> r1.189)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/timestamp.c?r1=1.188&r2=1.189)
    pgsql/src/include/catalog:
        catversion.h (r1.454 -> r1.455)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.454&r2=1.455)
        pg_proc.h (r1.495 -> r1.496)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h?r1=1.495&r2=1.496)
    pgsql/src/include/utils:
        timestamp.h (r1.77 -> r1.78)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/timestamp.h?r1=1.77&r2=1.78)