Device State:  Bug fix on camera rotation.

Render scene was ignoring devices_mouse values.
Fix mouse movement computation in device class.
Make update scene parametr take a devices_state as argument.  This enables us to
render different scenes and make sure the keyboard input was the same for each
scene.
Scene:  Remove window attribute

Window attribute is no longer needed as it used a device_state class in it's
update functions which does all the window querying.