Using UIGestureRecognizer and UIGestureRecognizerDelegate instead of a giant UIButton

These commits make it possible to remove the giant <code>UIButton</code> used to dismiss the tip view, and use a <code>UITapGestureRecognizer</code> on the <code>containerView</code> window instead. A single tap can now dismiss the tip view and also trigger any action associated with the tapped view object.