pgsql: Migrate rtree_gist functionality into the core system, and add

Log Message:
-----------
Migrate rtree_gist functionality into the core system, and add some
basic regression tests for GiST to the standard regression tests.
I took the opportunity to add an rtree-equivalent gist opclass for
circles; the contrib version only covered boxes and polygons, but
indexing circles is very handy for distance searches.

Modified Files:
--------------
pgsql/src/backend/access/gist:
Makefile (r1.14 -> r1.15)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/Makefile.diff?r1=1.14&r2=1.15)
pgsql/src/backend/utils/adt:
geo_ops.c (r1.89 -> r1.90)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/geo_ops.c.diff?r1=1.89&r2=1.90)
pgsql/src/include/catalog:
catversion.h (r1.283 -> r1.284)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.283&r2=1.284)
pg_amop.h (r1.64 -> r1.65)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_amop.h.diff?r1=1.64&r2=1.65)
pg_amproc.h (r1.53 -> r1.54)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_amproc.h.diff?r1=1.53&r2=1.54)
pg_opclass.h (r1.65 -> r1.66)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_opclass.h.diff?r1=1.65&r2=1.66)
pg_operator.h (r1.135 -> r1.136)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_operator.h.diff?r1=1.135&r2=1.136)
pg_proc.h (r1.372 -> r1.373)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.372&r2=1.373)
pgsql/src/include/utils:
geo_decls.h (r1.47 -> r1.48)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/geo_decls.h.diff?r1=1.47&r2=1.48)
pgsql/src/test/regress/data:
rect.data (r1.3 -> r1.4)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/data/rect.data.diff?r1=1.3&r2=1.4)
pgsql/src/test/regress/expected:
create_index.out (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/create_index.out.diff?r1=1.15&r2=1.16)
opr_sanity.out (r1.59 -> r1.60)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/opr_sanity.out.diff?r1=1.59&r2=1.60)
sanity_check.out (r1.25 -> r1.26)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/sanity_check.out.diff?r1=1.25&r2=1.26)
pgsql/src/test/regress/sql:
create_index.sql (r1.14 -> r1.15)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/create_index.sql.diff?r1=1.14&r2=1.15)
opr_sanity.sql (r1.47 -> r1.48)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/opr_sanity.sql.diff?r1=1.47&r2=1.48)

Added Files:
-----------
pgsql/src/backend/access/gist:
gistproc.c (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistproc.c?rev=1.1&content-type=text/x-cvsweb-markup)