move RemoveSelf activity into Mods/

OpenRA.Mods.RA/Activities/RemoveSelf.cs

@@ -0,0 +1,24 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2010 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made 
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see LICENSE.
+ */
+#endregion
+
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA.Activities
+{
+	public class RemoveSelf : CancelableActivity
+	{
+		public override IActivity Tick(Actor self)
+		{
+			if (IsCanceled) return NextActivity;
+			self.Destroy();
+			return null;
+		}
+	}
+}