pgsql: Add last-vacuum/analyze-time columns to the stats collector, both

Log Message:
-----------
Add last-vacuum/analyze-time columns to the stats collector, both manual and
issued by autovacuum. Add accessor functions to them, and use those in the
pg_stat_*_tables system views.

Catalog version bumped due to changes in the pgstat views and the pgstat file.

Patch from Larry Rosenman, minor improvements by me.

Modified Files:
--------------
pgsql/doc/src/sgml:
monitoring.sgml (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/monitoring.sgml.diff?r1=1.31&r2=1.32)
pgsql/src/backend/catalog:
system_views.sql (r1.26 -> r1.27)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/system_views.sql.diff?r1=1.26&r2=1.27)
pgsql/src/backend/postmaster:
pgstat.c (r1.125 -> r1.126)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgstat.c.diff?r1=1.125&r2=1.126)
pgsql/src/backend/utils/adt:
pgstatfuncs.c (r1.28 -> r1.29)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/pgstatfuncs.c.diff?r1=1.28&r2=1.29)
pgsql/src/include:
pgstat.h (r1.44 -> r1.45)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/pgstat.h.diff?r1=1.44&r2=1.45)
pgsql/src/include/catalog:
catversion.h (r1.332 -> r1.333)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.332&r2=1.333)
pg_proc.h (r1.411 -> r1.412)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.411&r2=1.412)
pgsql/src/test/regress/expected:
rules.out (r1.114 -> r1.115)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/rules.out.diff?r1=1.114&r2=1.115)