decide whether to add a 2-finger-drag Pointer Handler (or add feature to an existing one)

QtLocation needs this: when you move two fingers vertically, together, it tilts the map.

You could say that it's a kind of pinch, but so far we use that gesture to drag the target item. So, maybe you could disable dragging via some property, and maybe PinchHandler should have axis objects like DragHandler does, so that you can bind to the 2-finger vertical displacement somehow?

Another way is to make DragHandler inherit from QQuickMultiPointHandler, and support a configurable number of touchpoints, like PinchArea does. So if you set minimumPointCount to 2, it would not activate until you are dragging two fingers, and then it would use the centroid between them as the basis of the calculations.

Maybe it turns out that most handlers should inherit QQuickMultiPointHandler then. We could imagine a multi-finger TapHandler too.