harvest order wired into harvester. crashes with noti since the matching activity is noti.

OpenRa.Game/Cursor.cs

@@ -18,6 +18,7 @@ namespace OpenRa.Game
 		public Sprite GetSprite(int frame) { return sequence.GetSprite(frame); }
 		public int2 GetHotspot() { return sequence.Hotspot; }
 
+		public static Cursor None { get { return null; } }
 		public static Cursor Default { get { return new Cursor("default"); } }
 		public static Cursor Move { get { return new Cursor("move"); } }
 		public static Cursor Select { get { return new Cursor("select"); } }