pgsql: Changes * new split algorithm (as proposed in

Log Message:
-----------
Changes
* new split algorithm (as proposed in http://archives.postgresql.org/pgsql-hackers/2006-06/msg00254.php)
* possible call pickSplit() for second and below columns
* add spl_(l|r)datum_exists to GIST_SPLITVEC -
pickSplit should check its values to use already defined
spl_(l|r)datum for splitting. pickSplit should set
spl_(l|r)datum_exists to 'false' (if they was 'true') to
signal to caller about using spl_(l|r)datum.
* support for old pickSplit(): not very optimal
but correct split
* remove 'bytes' field from GISTENTRY: in any case size of
value is defined by it's type.
* split GIST_SPLITVEC to two structures: one for using in picksplit
and second - for internal use.
* some code refactoring
* support of subsplit to rtree opclasses

TODO: add support of subsplit to contrib modules

Modified Files:
--------------
pgsql/contrib/btree_gist:
btree_inet.c (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_inet.c.diff?r1=1.6&r2=1.7)
btree_interval.c (r1.7 -> r1.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_interval.c.diff?r1=1.7&r2=1.8)
btree_text.c (r1.8 -> r1.9)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_text.c.diff?r1=1.8&r2=1.9)
btree_time.c (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_time.c.diff?r1=1.10&r2=1.11)
btree_ts.c (r1.12 -> r1.13)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_ts.c.diff?r1=1.12&r2=1.13)
btree_utils_num.c (r1.7 -> r1.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_utils_num.c.diff?r1=1.7&r2=1.8)
btree_utils_var.c (r1.11 -> r1.12)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_utils_var.c.diff?r1=1.11&r2=1.12)
pgsql/contrib/cube:
cube.c (r1.25 -> r1.26)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/cube/cube.c.diff?r1=1.25&r2=1.26)
pgsql/contrib/intarray:
_int_gist.c (r1.13 -> r1.14)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/intarray/_int_gist.c.diff?r1=1.13&r2=1.14)
_intbig_gist.c (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/intarray/_intbig_gist.c.diff?r1=1.10&r2=1.11)
pgsql/contrib/ltree:
_ltree_gist.c (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/_ltree_gist.c.diff?r1=1.16&r2=1.17)
ltree_gist.c (r1.14 -> r1.15)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/ltree_gist.c.diff?r1=1.14&r2=1.15)
pgsql/contrib/pg_trgm:
trgm_gist.c (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_trgm/trgm_gist.c.diff?r1=1.6&r2=1.7)
pgsql/contrib/seg:
seg.c (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/seg/seg.c.diff?r1=1.17&r2=1.18)
pgsql/contrib/tsearch2:
gistidx.c (r1.13 -> r1.14)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/gistidx.c.diff?r1=1.13&r2=1.14)
query_gist.c (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/query_gist.c.diff?r1=1.6&r2=1.7)
pgsql/src/backend/access/gist:
Makefile (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/Makefile.diff?r1=1.15&r2=1.16)
gist.c (r1.138 -> r1.139)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gist.c.diff?r1=1.138&r2=1.139)
gistget.c (r1.57 -> r1.58)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistget.c.diff?r1=1.57&r2=1.58)
gistproc.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistproc.c.diff?r1=1.5&r2=1.6)
gistutil.c (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistutil.c.diff?r1=1.15&r2=1.16)
pgsql/src/include/access:
gist.h (r1.53 -> r1.54)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/gist.h.diff?r1=1.53&r2=1.54)
gist_private.h (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/gist_private.h.diff?r1=1.17&r2=1.18)