Enable multiple UIGestureRecognizer support.

Implement -(BOOL)gestureRecognizer:(UIGestureRecognizer
*)gestureRecognizer
shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer
*)otherGestureRecognizer UIGestureRecognizerDelegate method to support
multiple gesture recognisers that might conflict with the open / close
UIPanGestureRecognizers.