Beginning refactor, got rid of menu and game as instance variables for Game class, added last_surface instance variable for fading screens.
Reverted a change I didn't understand that broke menu highlighting, clean up a few other odds and ends.
Added a nicer looking font (Exo) for the game interface.
Merge branch 'features/refactor' of https://github.com/Perunity-PyGroup/perunity2048 into refactor
Minor fromat changes to conform to PEP8 standard.