Improved single player mode

-When pressing Single Player, the game wil now always start in sigle
player mode.
-MenuManager now holds whether the game is two player or not.
-AI Mode can now be toggled on and off using a
Implemented a working Lobby Menu

-Item underline when mouseover
-lobbyState to hold which button was clicked
-lobbyStateChanged to hold whether lobbyState has changed since last
time it was checked

TODO
-Check HasLobbyStateChanged first
	-If true, check lobbyState and act accordingly
	-If fasle, do nothing