Add RemoveImmediately trait for things that should only exist for one tick.

OpenRA.Mods.RA/OpenRA.Mods.RA.csproj

@@ -484,6 +484,7 @@
     <Compile Include="Widgets\Logic\ReplayControlBarLogic.cs" />
     <Compile Include="World\BuildableTerrainLayer.cs" />
     <Compile Include="Buildings\LaysTerrain.cs" />
+    <Compile Include="RemoveImmediately.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenRA.FileFormats\OpenRA.FileFormats.csproj">

OpenRA.Mods.RA/RemoveImmediately.cs

@@ -0,0 +1,22 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 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 COPYING.
+ */
+#endregion
+
+using OpenRA.FileFormats;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	public class RemoveImmediatelyInfo : TraitInfo<RemoveImmediately> {}
+
+	public class RemoveImmediately : INotifyAddedToWorld
+	{
+		public void AddedToWorld(Actor self) { self.Destroy(); }
+	}
+}