asyncCallback slows down application + fix

If the asyncCallback is called to fast the timeout is cleared (i think) and the callback is not triggered. To make it async a fix is made with requestAnimationFrame.

            //clearTimeout(timeout);
            //timeout=setTimeout(function() { if ( ft.callback ) { ft.callback(ft, events); } }, 1);
            requestAnimationFrame( function() { if ( ft.callback ) { ft.callback(ft, events); } } );

Could you apply this fix?

[AliasIO]

requestAnimationFrame is not supported in IE8 and IE9 though.

Another fix would be to remove the clearTimeout