- Fixed bug that affected many classes of event, particularly

- Fixed bug that affected many classes of event, particularly
ORM events but also engine events, where the usual logic of
"de duplicating" a redundant call to :func:`.event.listen`
with the same arguments would fail, for those events where the
listener function is wrapped.  An assertion would be hit within
registry.py.  This assertion has now been integrated into the
deduplication check, with the added bonus of a simpler means
of checking deduplication across the board.
fixes #3199

Conflicts:
	lib/sqlalchemy/event/registry.py
	test/base/test_events.py