Properly set direction of light.
Disable ambient lighting.
Attach lights to scene nodes to better move them around.  Parent doesn't have to be 
the root node.

Should be able to attach lights to models, as well as other lights.
Models can not yet be moved in this way.
Allow translation and rotation of lights based on parent node. Lights can still be moved inside of the parent node.
Allow setting of 3D orientation for Model objects.

Useful for level design things (static objects, etc) although it may not be useful in gameplay.
Update todo list.
Remember to at least return Qnil for c-extension code.
Define #reset_orientation for Light and Model
Remove C++ level animation fading code.
Bump version number.