Feature: added support for mask modifier.
SDK:
- remove unused imports in Nifty Editor that fail to compile on JDK8 (?)
Add RootNodeAppState, managing and updating a rootNode in an AppState
fix issue with setGravity/getGravity in native bullet
fix: examples/TestMultiRenderTarget.java to display tank (deferred) + encoded normal instead of black screen.
enhance TestMultiRenderTarget with small animation of light (rotating around 0,0,0 in 3s)
Merge pull request #178 from davidB/mrt_fix

fix: examples/TestMultiRenderTarget.java to display tank (deferred) + en...
https://github.com/jMonkeyEngine/jmonkeyengine/issues/179
Merge pull request #180 from Utlaen/patch-1

PhysicsCollisionEvent getPositionWorldOnA() stack overflow