Edited Unassigned: Add touch events to UIPlotElement [10114]

See [discussion:484239]

Implement touch events:
TouchDown
TouchMove
TouchUp

maybe also manipulation events?
ManipulationStarted
ManipulationDelta
ManipulationCompleted

number of fingers should be provided in event args.

What about gestures (pinch, double tap)?

Need to design this with touch API in iOS and android in mind.

http://msdn.microsoft.com/en-us/library/system.windows.uielement.touchdown(v=vs.110).aspx
http://docs.xamarin.com/guides/cross-platform/application_fundamentals/touch/part_1_touch_in_ios/
http://docs.xamarin.com/guides/cross-platform/application_fundamentals/touch/part_3_touch_in_android/