• dragging an event that lives on multiple resources should maintain the
  non-dragged resource IDs when dropped (#111)
• resources function/feed should receive start/end params (#246)
  (when refetchResourcesOnNavigate is true)
• iOS 10, unwanted scrolling while dragging events/selection (#230)
• timeline, clicking scrollbars triggers dayClick (#256)
• timeline, external drag element droppable when outside of calendar (#256)