Added frb.Circle class (#5)
Added property to determine if the mouse is over the canvas or not
Merge pull request #16 from KallDrexx/MouseOnCanvasProperty

Added property to determine if the mouse is over the canvas or not
added updateFunction hook to allow real-time replacement of user logic
Added an Emitter class
Circle now renders at the correctly offset coordinates
Internal sprite list is now using an attachable list. Also added reset function to SpriteManager
emitting a circle now resets the radius in case it was recycled.
Circle and Sprite now truly inherit from PositionedObject.

Brought in John Resig's simple inheritance to do the job. Also, a minor
change in that space bar is no longer disabled by default.
added frb.Line class
added clearColor option
Fixed issue with clearColor
Now calculating frb.viewBounds
now updating frb.viewBounds
rain sample improvements
viewBounds calc
rain Sample improvements
added loadedCallback to sprite add function
cleanup
new Sample for rendering tiles