adds getBounds() to Image class
Always output bounds in local coordinate
New Imagemask mask
Move getBounds to Imagemask
fix AtlasData to support Imagemask

- create() doesn't work on C++ code if receiving a BitmapData
- createRegion() doesn't copy Rect/Point which could cause reusing the same value.
Add collidePixelmask() for non flash targets using BitmapData
Merge pull request #126 from fserb/collide

adds getBounds() to Image class, add new Imagemask mask type