If we're on a touch-capable device, handle touches differently.

We might be scrolling!

See: https://github.com/GigaOM/legacy-pro/issues/4097
the comparison directions look a little suspicious to me, but i may not be reading the variables correctly.

if `$root.current_touch_y_pos` is the starting touch position as i read, then don't we want the comparisons to go the other way:
````
if ( $root.current_touch_y_pos + 10 < e.changedTouches[0].pageY || $root.current_touch_y_pos - 10 > e.changeTouches[0].pageY ) {
````
this is assuming `e.changedTouches[0].pageY` is the new touch position -- then we want it to be greater than the Y of the starting touch position plus 10, or less than the starting touch position minus 10.