Revert "Run graphics rendering on a dedicated thread."

This reverts commit b9be52c5428d4a3862d62fe3a2c01663bd3692c3.

OpenRA.Platforms.Default/ITextureInternal.cs

@@ -1,19 +0,0 @@
-#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);
-	}
-}