Add a SubCell field to UIM. Allow UIM to query for units by subcell.

OpenRA.Mods.RA/Husk.cs

@@ -10,6 +10,7 @@
 
 using System.Collections.Generic;
 using OpenRA.Traits;
+using OpenRA.FileFormats;
 
 namespace OpenRA.Mods.RA
 {
@@ -36,7 +37,7 @@ namespace OpenRA.Mods.RA
 
 		public int2 TopLeft { get { return location; } }
 
-		public IEnumerable<int2> OccupiedCells() { yield return TopLeft; }
+		public IEnumerable<Pair<int2, SubCell>> OccupiedCells() { yield return Pair.New(TopLeft, SubCell.FullCell); }
 		public int2 PxPosition { get { return Util.CenterOfCell( location ); } }
 	}
 }