macOS packaging using PyInstaller

Today is packaging day. Documented all third party artwork sources properly (we had notes, but now the list is complete, with only the artwork that remains in the final game release). Also, used PyInstaller for the first time to create a (hopefully self-contained) app bundle for easy running the game on macOS (this release has been uploaded as well, but you can also get the "source" release and run it with your local Python 3 (+PyGame + PyOpenGL):

macOS packaging