Added EventAction and CountdownEventAction.

http://www.badlogicgames.com/forum/viewtopic.php?p=56079#p56079
Javadocs
PolygonSpriteBatch now implements Batch.
Changes
GWT Reflection: simplified generated code
The Reflection Cache uses now integer ids instead of strings for type/method/constructor lookups. This greatly simplifies the generated code.
Merge pull request #1273 from hneuer/gwtr

GWT Reflection: simplified generated code