Refactor ScreenSpaceEventHandler and the tests substantially.
Hook up pointer events.
fix specs for pointer events
Merge remote-tracking branch 'origin/master' into pointerEvents
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Merge remote-tracking branch 'origin/master' into pointerEvents

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Merge remote-tracking branch 'origin/master' into pointerEvents

Conflicts:
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Merge remote-tracking branch 'origin/master' into pointerEvents

Conflicts:
	CHANGES.md
Merge pull request #2253 from AnalyticalGraphicsInc/pointerEvents

Add initial support for Pointer Events for both mouse & touch (IE11)