Refactor actor and controller

There was a lot of functionality on the controller that I wanted to move
to actors. Namely, all of the game and logic functionality. The controller
should really only manage transitions and be responsible for managing
the NSOpenGLView and keeping the window around.
Correctly clear color in between frames

Since I was clearing the buffer with glClearColor(0, 0, 0, 0),
weird things will happen with a black color that has a zero
alpha value. Apparently this would cause the graphics to be
drawn with what appeared to be inverted colors. Changing
this to be a fully opaque black color fixes this issue.