Disable pan-to-the-right gesture recognition if right drawer is empty.

[NKorotkov]

This is a feature request. I have an app that only makes use of left menu drawer. But anytime a user pans across centre controller in the right direction pan gesture is not cancelled. It creates a lot of headache and conflicts a lot with other gesture. It would be really helpful to create an option that makes main pan gesture fail immediately if there's no side drawer at that position. It can be achieved through subclassing UIPanGestureRecognizer that cancels itself in - (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event . Please consider this in future versions.