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/opengl/Texture.h

@@ -38,7 +38,7 @@ class Texture final : public love::graphics::Texture, public Volatile
 {
 public:
 
-	Texture(const Settings &settings, const Slices *data);
+	Texture(love::graphics::Graphics *gfx, const Settings &settings, const Slices *data);
 
 	virtual ~Texture();