Add flipping of Y in mouse position.
Add mouse pos adjustments based on window size.

You can now turn on SetNativeMousePos, which keeps reported mouse
positions relative to the native window size.
Add methods for getting and setting Window size.

It's about time.
Add methods to get/set native Window size.
Fix Window object to adhere to Paunch standards.

Now the Window object has a New[x] method like other objects and
initialization of the window system is explicit. Opening the window can
now be done after creation.
Fix Effect object to also follow the Paunch way.

The Init method was turned into a NewEffect function.