Touch simulation improvements

- Support for more complex multitouch gestures. One can pan like
before, but then add a second finger during panning as well as
transition from two fingers to one finger.
- The simulated touches can be dragged together by holding down the
left shift key.
- Bugfix for the delta position of the simulated second finger (before,
the delta position was the same for both fingers)
- Bugfix that caused flickering of the visualized touches
- Simulated touches now also deliver touches in the Stationary phase
for more realistic simulation
- Improved the inspector view by grouping together debug settings and
enabling/disabling obsolete settings during configuration
- All touches can now be visualised for debug purposes, to also
visualise the touches received from a Unity remote