Add a postUpdate function to plugins, which is called after World.postUpdate
fix #154 Button now goes back to over state when setFrames used in action
Mouse property to say what button is being clicked

It follows the convention that already was in the
file 0 for left, 1 for middle and 2 for right.
It also changes to -1 when mouseUp.
Check type uses the static values
fix typo
getAnimation and RAF callback ID checks added
Merge pull request #167 from wKLV/dev

Mouse now knows what button is clicked
Merge pull request #162 from beeglebug/button

Button now goes back to over state when setFrames used in action
Merge pull request #160 from cocoademon/camera_shake

Add a postUpdate function to plugins
Mouse handler updates.
Input Handler updates, orientation screen and World visibility
Added Tetris sprites