Special event processing for LastChange events

--HG--
extra : rebase_source : d79713bd55186a54bfc844a840da3ae49c083ca4
Add crossfade
Remove code changes.  Replace with test/doc fix for cross_fade
Merge remote-tracking branch 'upstream/master' into crossfade

Conflicts:
	unittest/test_core.py
Merging with master
Camel to underscore var names, and some more docs
Updating tests for camel_to_underscore conversions
Refactor Event to be an object.

The evented variables are now accessible as attributes on the event object
events now return music data structures where relevant
Minor doc fixes
Merge pull request #194 from lawrenceakka/last-change-events

Special event processing for LastChange events. Thanks to all for comments
Merge pull request #215 from dajobe/crossfade

Document cross_fade property and add test for it
Add Release notes for 0.9