Fixed DOMException handling when zero-by-zero HTMLCanvasElements are copied via the Fizz.Canvas class; added basic 'mousemove' event dispatching to Fizz.Canvas and Fizz.Stage classes; added copying of cacheCanvas elements between DisplayEntities on copy/clone; Fizz.DisplayGrid now accounts for scale.x and scale.y when calculating child layouts; fixed positioning/scaling of children when DisplayGroup instances are cached;