1.33 Update

* Updated comments and added examples
* Modified engine so that Box2D can be safely excluded if not needed
* TheApp now supports dynamic canvas calling to fit the canvas to the
browsers client area, supports scale to fit to x-y axis or resize to
client area, see TheApp.canvas_scale_method.
TheApp.setCanvasScalingMethod can be used to change method
* Added new functions to TheApp, Scene and Actor that can dirty all
transforms and force an update
* TheApp now stores canvas size (canvas_width, canvas_height), display
size (display_width, display_height), canvas scale and centre points and
device pixel ratio (pixel_ratio)
* TheApPp now has touch_supported property that  is set to true if touch
is supported
* TheApp now has new property called dt which represents the time passed
since the last frame was updated
* ImageAtlas generation now supports start x and y position which
enables an image offset to be specified
* Xoml loader now supports text_align, text_baseline and fill_stye
properties
* Added Actor._scale property
* Added Actor.changeParent(actor, parent) that enables actors to be
moved from one parent to another
* Added Actor.findFirstParent() which finds the first Actor based parent
* Added Actor.transformPoint() that ca be used to transform a point into
the actors coordinate system
* ParticleActor.add() has a 5th parameter called orphaned, if set to
true then the particle will be added to the scene and not the particle
actor