Add a lint check for cursor definitions.

OpenRA.Mods.Common/Orders/BeaconOrderGenerator.cs

@@ -30,7 +30,7 @@ namespace OpenRA.Mods.Common.Orders
 		protected override IEnumerable<IRenderable> RenderAnnotations(WorldRenderer wr, World world) { yield break; }
 		protected override string GetCursor(World world, CPos cell, int2 worldPixel, MouseInput mi)
 		{
-			return "ability";
+			return "ability"; // TODO: [CursorReference]
 		}
 	}
 }