Use use touch events to generate mouse events in Quick canvas.

Use use touch events to generate mouse events in Quick canvas.

Allowing the canvas to deal with mouse event emulation provides
a couple of advantages: 1. touches outside a reactive area can
be ignored, allowing a touch within a reactive area to become
the "mouse touch". 2. we can extend the mouse events with
data available in touch events for use within the quick elements;
specifically velocity in this case.

Change-Id: Id9df397f1a3a03dbda2ef5dcf6189e7eb3377356
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>