Add resize event and change hitbox on resize

This patch:
* Adds a resize event to "2D" triggered when h or w change
* Allow "Collision" hitboxes to track an entities shape through that event
* Change collision(polygon) to rotate the polygon before attaching it
* Fix some errors in calculating the MBR when a rotated entity was resized
* Adds some tests for resizing rotated objects
Merge pull request #485 from starwed/resize

Add resize event and change hitbox on resize
Refactor DrawManager.draw into separate routines triggered by an event

Instead of directly calling Crafty.DrawManager.draw(), this patch triggers a "RenderScene" event.  draw() is now split between two functions; renderCanvas() and renderDOM().  Using an event instead of a hardcoded function call should make it possible to add new types of rendering.
Create a debug layer

* Add a debug canvas and a base "DebugCanvas" component
* Create several components that build additional functionality on top of the debug canvas
* Add tests and docs