Implement cnc harv/proc dock sequence and kill unnecessary duplication. Bad things happen if sequence is interrupted by another order (eg invisible harv).

Still todo: Make sequence non-interruptible; engineer steals harv docked with proc; the "right thing" if proc is sold/destroyed with harv docked.

OpenRA.Mods.RA/TraitsInterfaces.cs

@@ -30,4 +30,9 @@ namespace OpenRA.Mods.RA
 		void UnlinkHarvester(Actor self, Actor harv);
 		int2 DeliverOffset { get; }
 	}
+	
+	public interface IAcceptOreDockAction
+	{
+		void OnDock(Actor self, Actor harv, DeliverResources dockOrder);
+	}
 }