Rewrite Leap activity to be more robust.

The dog will now always leap to the target
subcell (even if the target dies or moves),
and will kill whatever happens to be in the
target cell when it lands.

OpenRA.Mods.RA/Move/Mobile.cs

@@ -170,7 +170,9 @@ namespace OpenRA.Mods.RA.Move
 
 		public void SetLocation(CPos from, SubCell fromSub, CPos to, SubCell toSub)
 		{
-			if (fromCell == from && toCell == to) return;
+			if (fromCell == from && toCell == to && fromSubCell == fromSub && toSubCell == toSub)
+				return;
+
 			RemoveInfluence();
 			__fromCell = from;
 			__toCell = to;