Re: KNNGiST for knn-search (WIP)

Changes:

- split patch to several ones
- sync with current CVS

Patch set is based on 0.5.1 version, difference between 0.5 and 0.6 should be 
only in planner patch.

builtin_knngist_itself-0.6.gz  - patch to the gist itself
builtin_knngist_proc-0.6.gz - patch for support knnsearch in point_ops
builtin_knngist_planner-0.6.gz - planner patch to support knnearch
builtin_knngist_contrib_btree_gist-0.6.gz - patch for contrib/btree_gist module
                patch provides <-> operation for various scalar types which is
                exactly  abs(a - b) function
builtin_knngist_contrib_pg_trgm-0.6.gz - contrib/pg_trgm, like above,patch
                provides <-> distance between strings


Patch set sill requires rbtree patch and point_ops patch (with Robert's changes)

-- 
Teodor Sigaev                                   E-mail: teodor@sigaev.ru
                                                    WWW: http://www.sigaev.ru/