Fixes and additions to Graphics

Even has a hitTest method (in preparation to global implementation) now.
Rewrote the whole of MouseEvent handling

Possibly a breaking change; work in progress.
Mouse events are now routed through DOM by backend rather than browser.
Graphics and BitmapData objects now have precise hit tests for mouse
events.
Touch events should be converted to mouse events even on strangest
browsers.
Feedback is appreciated.