Fixed race condition that affected Android + Chrome on mobile when a "scratchDown" callback was also setup. Fixed involves deferring callbacks so that "touchstart" will return immediately on touch devices due to delay caused by calculating percentage which is passed into all callbacks (including 'down'). Chrome will trigger a "touchcancel" event if not responding after 200ms. Also ensuring all callbacks (down/move/up) are called all the time except "move" which should be called only when "realtime" is set.