Fix #1348 -- Tesla Coils now support Stop (S) order

OpenRA.Mods.RA/Attack/AttackTesla.cs

@@ -51,6 +51,14 @@ namespace OpenRA.Mods.RA
 			return new TeslaAttack( newTarget );
 		}
 
+		public override void ResolveOrder(Actor self, Order order)
+		{
+			base.ResolveOrder(self, order);
+
+			if (order.OrderString == "Stop")
+				self.CancelActivity();
+		}
+
 		class TeslaAttack : Activity
 		{
 			readonly Target target;