Split off last bot modules

And dissolve AI namespace.
There would have been so little left in Common.AI,
that keeping it made no sense anymore.

OpenRA.Mods.Common/Traits/BotModules/BotModuleLogic/SupportPowerDecision.cs

@@ -10,7 +10,6 @@
 #endregion
 
 using System.Collections.Generic;
-using OpenRA.Mods.Common.AI;
 using OpenRA.Primitives;
 using OpenRA.Traits;