now allowing batching of QuadBatches via the new 'batchable' property.

Right now, used by the TextField class for short texts (less then 16 chars).
replaced automatic TextField batching with "batchable" property users can activate manually.

Otherwise, non-batchable texts (e.g. because the font texture is not in the atlas) would actually be rendered slower than before.
optimization: avoiding assignment by using if instead of ternary operator
small code changes to avoid warnings/errors in FDT
optimized broadcast of ENTER_FRAME event (closes #311)

This solution doesn't change the behaviour in any significant way, and it should be absolutely safe when it comes to garbage collection (even when people forget to call "dispose" on the object).
only listening to context loss event when context loss handling is enabled
Merge branch 'master' of https://github.com/PrimaryFeather/Starling-Framework into performance

Conflicts:
	starling/src/starling/core/RenderSupport.as