Fixed bug in ORM-level event registration where the "raw" or
"propagate" flags could potentially be mis-configured in some
"unmapped base class" configurations.  Also in 0.8.3.
[ticket:2786]
apply fix from [ticket:2786] to the ticket_2268 branch
express the append() and insert() methods in terms of the _EventKey
actually make this test work
express remove in terms of event_key
express all movement of listener functions to/from/between all lists/sets
in terms of _EventKey, so that we're ready to track all these membership changes.