Movement relative to orientation.

Entities can now be moved via their forward() and backward()
functions, which handle all the calculations for moving them
with respect to their angle.
Cleaned up globals, fading.

Some errant global variables had inadvertently been created.
These were localized. Also, the ui has a new fade() function
that makes entities transparent with an adjustable rate.
Thinking that scales_mapper now needs to be refactored or
dropped entirely to work with the new entity framework.
Make vcam limits optional.
Updating API calls to LOVE 0.9.0.
Caught a few more necessary API updates.