Revert "first cut working commit triggers"

This reverts commit 6682790047e58c2c06757dd9d5e8a77ccdee35e4.

Conflicts:

	src/backend/access/transam/xact.c
	src/backend/commands/event_trigger.c
	src/include/utils/evtcache.h
fix conflict left from last commit
one more revert
Merge branch 'jsonb_and_hstore' of github.com:feodor/postgres into jsonb
Remove DESCR entries for jsonb operator functions.
Add JsonbValueToJsonb() function.

Per Teodor's suggestion.
Rewrite jsonb_array_element* using native jsonb API.