fix to current class model

[RhinoLu]

No description provided.

[lannymcnie]

This port is not quite complete.

1. The initialize method has been deprecated in favor of using the constructor
2. Properties should no longer be declared on the prototype, but rather initialized and document inside of the constructor.
3. The new extend/promote removes the need for the p.DisplayObject_function = p.function approach, so those should be removed.

I also recommend changing the .addEventListener usages in the demo to .on().

If you can address these changes, I will accept the PR. Thanks for updating this class, and sorry for the late response!