added SpeedTester.as. currently just tracing. roadmap will be adding a
debug window for mobile testing.
added "dispatchAddedEvent" boolean in Starling's DisplayObjectContainer
and DisplayObject. This will significantly speed up if you're about to
add hundreds to thousands of object, also, when transferring an object
from 1 parent to another. NOTE THAT THIS IS STILL UNDER TESTING FOR SOME
ISSUES NOT DISPATCHING ADDED EVENT.