Completely removed country info from HighScoreTable

-Adjusted list indices
-Temporarily disabled scoreoid_highscoretable.py
Added centering of HudObjects

-Implemented as a_hud_object.center() which returns self
-Centered various text on MainMenu, HighScoreState, and InGameState
-Added the current wave in InGameState (at the bottom of the screen)
-Added text to ingame-xx.wtf to reflect this
-Added a field to gamedata and ingame.HUD_TEXT to reflect this
-Also fixed a bug in selecting language
Tidied up code a little bit

-Made the game window close immediately upon exit
-So the window doesn't linger while the rest of the game is still cleaning up