Emulated drag should not start when clicked and not moved
Support 'cancel' query String to prevent dragging

* A 'cancel' query String may be supported for draggables to prevent
  starting a drag on specific elements.
* Improve clearing of selection when drag starts.
Register touchMove and touchEnd events with touchStart

* TouchMove and TouchEvents should only be listened to when a 
  touch started. This is now the same as with emulated mouse events.
* This also fixes a bug that drag elements were created when touching
  and not moving but not removed.
* Also supporting 'cancel' query String in touch emulation.
New example for preventing drag start with 'cancel' query String