add ActionQueue, rather than leaving random variables lying around in Game.cs

OpenRA.FileFormats/Primitives/ActionQueue.cs

@@ -0,0 +1,40 @@
+#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 System;
+
+namespace OpenRA.FileFormats
+{
+	/// <summary>
+	/// A thread-safe action queue, suitable for passing units of work between threads.
+	/// </summary>
+	public class ActionQueue
+	{
+		object syncRoot = new object();
+		Action actions = () => { };
+
+		public void Add(Action a)
+		{
+			lock (syncRoot)
+				actions += a;
+		}
+
+		public void PerformActions()
+		{
+			Action a;
+			lock (syncRoot)
+			{
+				a = actions; 
+				actions = () => { };
+			}
+			a();
+		}
+	}
+}