Merge FileFormats dll into Game and reorganise namespaces.

OpenRA.Renderer.Sdl2/Sdl2GraphicsDevice.cs

@@ -11,7 +11,8 @@
 using System;
 using System.Drawing;
 using System.Linq;
-using OpenRA.FileFormats.Graphics;
+using OpenRA;
+using OpenRA.Graphics;
 using OpenRA.Renderer.Glsl;
 using OpenRA.Renderer.SdlCommon;
 using SDL2;