metal: nogame and error screens work.

- implement love.graphics.setColor
- implement default textures
- hacky implementation of default uniform data
- use texture swizzles to set up LA8 (text) texture data
- shader reflection work

src/modules/graphics/Texture.h

@@ -201,7 +201,7 @@ public:
 
 	static int64 totalGraphicsMemory;
 
-	Texture(const Settings &settings, const Slices *slices);
+	Texture(Graphics *gfx, const Settings &settings, const Slices *slices);
 	virtual ~Texture();
 
 	// Drawable.