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
Merge pull request #160 from fredj/dblclick-unlisten

Remove event listener cleanups