Rendertarget attachments, texture and image changes (#358)

* Add multiple color outputs for fragment shaders

* Add registers and gal enums

* Use textures for framebuffers and split color and zeta framebuffers

* Abstract texture and framebuffer targets as an image

* Share images between framebuffers and textures

* Unstub formats

* Add some formats

* Disable multiple attachments

* Cache framebuffer attachments

* Handle format types

* Add some rendertarget formats

* Code cleanup

* Fixup half float types

* Address feedback

* Disable multiple attachments in shaders

* Add A4B4G4R4 image format

* Add reversed section for image enums

Ryujinx.HLE/Gpu/Engines/NvGpuEngine2d.cs

@@ -154,16 +154,12 @@ namespace Ryujinx.HLE.Gpu.Engines
             }
             else if (IsDstFb)
             {
-                //Texture -> Frame Buffer copy.
-                const GalTextureFormat Format = GalTextureFormat.A8B8G8R8;
-
                 byte[] Buffer = TextureReader.Read(Vmm, SrcTexture());
 
                 Gpu.Renderer.FrameBuffer.SetBufferData(
                     DstKey,
                     DstWidth,
                     DstHeight,
-                    Format,
                     Buffer);
             }
             else