WheelHandler with both orientations at the same time

Most recent touchpads allow vertical and horizontal panning so it would make sense for WheelHandler to be able to use both at the same time. Currently WheelHandler can only handle one orientation so two instances of it would be needed to handle something like a scrolling a large image around.

Maybe in both orientations mode it could use new property that is of type QPointF (instead of the rotation property) to store the current value, and also if the target is set, it would send QPointF to it.