fixing z-order; generalized the 1x1 placement fix to handle nx1 (which were ALL wrong)

OpenRa.Game/GameRules/Footprint.cs

@@ -57,10 +57,7 @@ namespace OpenRa.Game.GameRules
 		public static int2 AdjustForBuildingSize( UnitInfo.BuildingInfo unitInfo )
 		{
 			var dim = unitInfo.Dimensions;
-			if (dim.X == 1 && dim.Y == 1)
-				return int2.Zero;	/* otherwise 1x1 buildings look stupid */
-
-			return new int2( dim.X / 2, ( dim.Y + 1 ) / 2 );
+			return new int2( dim.X / 2, dim.Y > 1 ? ( dim.Y + 1 ) / 2 : 0 );
 		}
 	}
 }

OpenRa.Game/Graphics/WorldRenderer.cs

@@ -51,7 +51,7 @@ namespace OpenRa.Game.Graphics
 			var rect = new RectangleF((region.Position + Game.viewport.Location).ToPointF(), 
                 region.Size.ToSizeF());
 
-			foreach (Actor a in Game.world.Actors)
+			foreach (Actor a in Game.world.Actors.OrderBy( u => u.CenterLocation.Y ))
 				DrawSpriteList(a.Owner, rect, a.Render());
 
 			foreach (IEffect e in Game.world.Effects)