Special event processing for LastChange events

--HG--
extra : rebase_source : d79713bd55186a54bfc844a840da3ae49c083ca4
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