Add a handful of methods for working with views.
Add a handful of methods for working with views.

- handle_event - Empty method. Should handle the received event or
  ignore it and let it continue to propagate.
- scale_factor - just grabs the window's scale factor. If not attached
  to a window, this is obviously going to fail.
- views_containing_point - returns an array of views that contains the
  given point. Recursive. Should probably start with leaf views since
  they'll ideally be cached by the window.
- convert_to/from_root - Simply converts a point to and from the root
  view's coordinate space.
- window and root_view, ideally, return the same thing.
- each_superview - iterates over superviews or returns an enum.

nilium/ruby-gui,nilium/ruby-gui,nilium/ruby-gui