Toplevel module, resources, init SDL systems

* Import a bunch of graphical resources for use later.
* The beginnings of the toplevel module, which will be used to interact
with the window and surface system from within Python.
* Call SDL_Init when we start up, and SDL_Quit when we're finished
before exiting through Py_Exit.
* Remove PySys_SetPath so we can still access the system Python library
- Instead, prefix our PyDoom.zip before it so we can always find our
modules first, even if they match the names of existing ones.