Properly special case first single touch; fall
back to allow windows to emulate mouse events for it.
Yet let gdk handle any multi-touch events, not allowing gestures.
* Fix special case of first single touch. While another touch
is active, any new touch must not get the ID of the (ignored)
first touch.
* reset "last-touch" coordinate on touch-begin.
Previously it was possible that the first motion event was
ignored.
NB: This does not fix missing events when the first touch
coincides with any other finger (gesture?).
Gestures may prevent a 2nd touch from being registered as
such (and instead report a zoom/pinch gesture).
At least that is my best guess, why Nathan needs 3 fingers
to move 2 Faders :)
recent gcc (>=11) sets _WIN32_WINNT >= 0x602 which changes
QS_ALLINPUT to include (QS_TOUCH | QS_POINTER) events which are
only available on Windows 8 and later. Listening to those events
makes ardour unresponsive.
