Make example work on touch screen as well.#1

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codecurve wants to merge 4 commits intotparisi:masterfrom

codecurve:touch-and-mouse

Commits on Jul 17, 2013

Make example work on touch screen as well (e.g. Firefox on Android on Samsung Galaxy S3).
Randall Britten
committed
Mostly eliminate response to multiple touches on canvas, so that only single touch dragging is processed.
Randall Britten
committed

Commits on Jul 18, 2013

Moved processDrag function to end of the group of mouse/touch handling functions for neater flow.
Randall Britten
committed
Using targetTouches rather than changedTouches seems to help avoid "multi-touch" misinterpretations, based on playing around.
Randall Britten
committed