Merge pull request #1 from x3dom/master

update from x3dom
fix mouse up on chrome ( mac and windows touch)

mouse up is recognized by an additional mouse move event with button=0,
but it seems like this event is not fired on mac or on touch input.
checking for the mouse up flag fixes this.
Merge pull request #404 from dschie/master

fix mouse up on chrome ( mac and windows touch)