A first aproximation to pinch and zoom implementation in MockupSceneEdit...

...or.
Because the second finger (pointer 1) must also execute a dragStop event as invoked here: https://github.com/e-ucm/ead/pull/629/files#diff-3971a405ba3804130a1b5485685dbdf6R366 so we assure that we're not selecting with the second finger while also scaling/rotating.