Merge pull request #1 from UltimateKaveman/master

Merged pull request #1 from UltimateKaveman. Request to add utility files to main repository.
Update GameCamera.as. Removed debug functions and cleaned up.

- Dumbed down focus formulas
- Removed debug functions
- Made GameCamera() throw an error when instantiated
- No need for GameCamera to extend Sprite
Removed Camera from GameScreen.as

I'm planning on using Component-Based Entities, so instead of placing all objects in the GameCamera, I am going to allow them to offset their position by the 'focusX' and 'focusY'.
Update MouseHandler.as, made more like a singleton

Moved around class, made reference to stage. Removed lockout, moved constructor setup to start()
Fixed Comments in MouseHandler.as
Fixed COmments in MouseHandler.as #2