Removed some GameState functions in favor of itertools.partial

-itertools.partial returns a function with the arguments partially filled in
-Added GameState.change_state()
-Consolidated HighScoreState.__char_up/down into char_move
-Moved the contents of HighScoreState.__update_name() into __char_move
-Applied itertools.partial and GameState.change_state() to InGameState
-Removed five extraneous functions from MainMenu in favor of the above changes
-Did a similar thing in SettingsMenu
-Also consolidated the Settings menu's entries into a dict
Moved player.STATES into player.Ship.STATES

-Also adjusted enemybullet.py to reflect this