Laying down some ground work for the keepaway game mode, lots more work to do for...

Laying down some ground work for the keepaway game mode, lots more work to do for this to be functional but i'm too tired and I have work tomorrow morning. Currently the TODO list for tomorrow: Finish core game mode so that it at least compiles, do the HUD for keepaway, add code to bot/aim.qc which makes bots only attack carrier, add the cvars needed for the game mode to defaultXonotic.cfg, and decide on just ONE way to refer to keepaway (KA or keepaway?)