Fixes two-finger gestures on the iPad touchscreen.
The two-finger right click added in 1.0.6 never fired: the pan recognizer claimed the touches and began before the tap could complete. It now waits for the tap to fail first.
Zooming in 1.0.6 also emitted a spurious right click alongside the zoom, because the pinch and the two-finger tap were allowed to recognize simultaneously. They are now mutually exclusive, so a spread zooms and nothing else.
Also adds a UI-test harness that drives real multi-touch against the pointer capture view, since recognizer arbitration cannot be exercised from a unit test.