Add a comment about msTouchAction css on viewport
Add missing goog.events.EventType.DBLCLICK argument to unlisten
Remove event listener with goog.events.unlistenByKey
Don't remove event listener for this.handleUp_ twice.

The listener key is in this.dragListenerKeys_
Remove event listener with goog.events.unlistenByKey
Do not draw image if image is null
Merge pull request #161 from elemoine/nullimage

Do not draw image if image is null
Merge pull request #160 from fredj/dblclick-unlisten

Remove event listener cleanups
Rename MapBrowserEventHandler internal handlers name
Remove touch events handling in handleMouse* handlers
Add listeners for touchstart, touchmove and touchend events
Listen to IE pointer events