Small OpenGL Renderer refactoring (#177)

* Call OpenGL functions directly, remove the pfifo thread, some refactoring

* Fix PerformanceStatistics calculating the wrong host fps, remove wait event on PFIFO as this wasn't exactly was causing the freezes (may replace with an exception later)

* Organized the Gpu folder a bit more, renamed a few things, address PR feedback

* Make PerformanceStatistics thread safe

* Remove unused constant

* Use unlimited update rate for better pref

Ryujinx.HLE/Gpu/Texture/ISwizzle.cs

@@ -0,0 +1,7 @@
+namespace Ryujinx.HLE.Gpu.Texture
+{
+    interface ISwizzle
+    {
+        int GetSwizzleOffset(int X, int Y);
+    }
+}