Run graphics rendering on a dedicated thread.

The main game thread can offload some of the CPU cost to the rendering thread, freeing up its time to run more logic and render ticks.

OpenRA.Platforms.Default/ITextureInternal.cs

@@ -0,0 +1,19 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2018 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, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+namespace OpenRA.Platforms.Default
+{
+	interface ITextureInternal : ITexture
+	{
+		uint ID { get; }
+		void SetEmpty(int width, int height);
+	}
+}