- Fixed potential memory leak which could occur if an
arbitrary number of :class:`.sessionmaker` objects
were created.   The anonymous subclass created by
the sessionmaker, when dereferenced, would not be garbage
collected due to remaining class-level references from the
event package.  This issue also applies to any custom system
that made use of ad-hoc subclasses in conjunction with
an event dispatcher.  Also in 0.7.10. [ticket:2650]

:meth:`.MutableBase.coerce` method to be used, even though
the code seemed to indicate this intent, so this now works
and a brief example is added.  As a side-effect,
the mechanics of this event handler have been changed so that
new :class:`.MutableComposite` types no longer add per-type
global event handlers.  Also in 0.7.10

[ticket:2624]

    mapped classes allows that unmapped classes
    can be specified for instance- and mapper-events.
    The established events will be automatically
    set up on subclasses of that class when the
    propagate=True flag is passed, and the
    events will be set up for that class itself
    if and when it is ultimately mapped.
    [ticket:2585]

  - [bug] The instrumentation events class_instrument(),
    class_uninstrument(), and attribute_instrument()
    will now fire off only for descendant classes
    of the class assigned to listen().  Previously,
    an event listener would be assigned to listen
    for all classes in all cases regardless of the
    "target" argument passed.  [ticket:2590]

    fires off for so-called "_cursor_execute"
    events, which are usually special-case
   executions of primary-key bound sequences
    and default-generation SQL
    phrases that invoke separately when RETURNING
    is not used with INSERT.  [ticket:2459]

usage of the event system; instance-level
collections are no longer created for a
particular type of event until
instance-level listeners are established
for that event.  [ticket:2516] Also in 0.7.9.