added fix for all bound events responding to all instances

due to the way the events class was being mixed0-in directly onto the prototype, every instance of the Animation class shared the same event handlers. This mixes in the Event class in the Animation contructor, giving each instance a separate handlers array.

Signed-off-by: Darcy Adams <darcy.adams@wellogic.com>
Merge pull request #1 from darcyadams/event-handler-fix

added fix for all bound events responding to all instances