Implement automatic batching for points, lines, shapes, and images/quads.

The above are batched together into a single draw call when called without other drawing calls in between, as long as the following criteria are met:

- The texture is the same.
- The primitive type is the same (points cannot be batched with non-points).
- The love.graphics state is the same (aside from the current color - i.e. setColor - and the transform state).
- The active shader’s uniform values are the same.

You can examine the ‘drawcalls’ field of love.graphics.getStats() to help determine if your code is allowing for optimum batching.

--HG--
branch : minor

src/modules/graphics/opengl/Text.h

@@ -52,7 +52,7 @@ public:
 	void clear();
 
 	// Implements Drawable.
-	void draw(const Matrix4 &m) override;
+	void draw(Graphics *gfx, const Matrix4 &m) override;
 
 	void setFont(Font *f);
 	Font *getFont() const;