Improved docs for icon options
Merge pull request #2903 from elemoine/icon-docs

Improved docs for icon options
Remove 'pointerup' listener in ol.control.FullScreen
Remove 'pointerup' listener in ol.control.Zoom
Remove 'pointerup' listener in ol.control.Rotate
Remove 'pointerup' listener in ol.control.ZoomToExtent
Remove 'pointerup' listener in ol.control.Attribution
Remove 'pointerup' listener in ol.control.OverviewMap