touchpad: disable the immediate scroll state if tapping is enabled
On a touchpad without gestures we would take a 2-finger touch as immediate start to a 2-finger scroll gesture. This effectively removes the 1mm threshold we otherwise have before scrolling is assumed to have started.
If tapping is enabled and a user triggers a small motion event this results in scroll events being sent before the two-finger tap.
Closes #981 (closed)
cc @toonn