TODO item - tid <> operator

Please find enclosed a patch that adds a '<>' operator for tid types
(per TODO item). Patch is against current sources (beta4).

If I have understood the requirement properly, the relevant function
'tidne' already existed in src/backend/utils/adt/tid.c, just needed an
ifdef NOT_USED removed. The '<>' operator however, needed to be added.

I have renumbered the OIDs for the various tid functions in order to
keep them together with the 'new' tidne one in pg_proc.h - as we have
run out of OIDs in the old range. Similarly for the '=' operator in
pg_operator.h.

with the patch applied, all 98 regression tests pass, plus it seems to
work ok :-)

test=# select ctid, id from foo where ctid != '(0,1)';
ctid | id
-------+----
(0,2) | 2
(0,3) | 3
(2 rows)

regards

Mark