DirectionalDragArea & friends: various improvements & API grooming
-Simplified DirectionalDragArea gesture recognition * The widening angle property was dropped. Didn't really work as in real life swipes might start up in very different directions before finally turning to the final overall direction. That's specially bad when you have to conclude the recognition in a short amount of time so that you can still play animations to follow the user's finger * minSpeed as well. Went for a simpler way of expressing and evaluating it which is having maxTime and maxDistance.
-EdgeDragArea got absorbed by DirectionalDragArea
-Privatized all gesture recognition parameters.
-Privatized DirectionalDragArea.status property. All apps need is DirectionalDragArea.dragging. Modified qml code using DDA accordingly.
-Modified DirectionalDragArea.dragging semantics a bit. It goes to true only once a gesture is recognized
-Moved code that smooths out touch movement into DirectionalDragArea so all users get it for free.
-Cleaned up DirectionalDragArea.h of all implementation details, getting it ready to be moved out of unity8, into the SDK.
-Removed DirectionalDragArea.tapped() signal as it doesn't belong to it.
-Fine-tuned gesture recognition parameters and made them based on physical size.
-Added tests with input from real gestures to catch those annoying false-negatives and false-positives introduced by badly set recognition parameters
-Improved debug output
-UnownedTouchEvents are no longer sent to interim owners
-Fixed issue when TouchGate got disabled while holding an active touch
-Made "make tryDirectionalDragArea" and "make tryDragHandle" work with mouse again.