Pass Renderer2D to Renderable and have each subclass of Renderable decide what the Renderer should do (like drawText(), drawRect() etc).
This makes the Renderable more flexible. right now, each renderable has a texture, vertices and indices. but what if some renderables does not use textures? or more than one? What if some renderables are just a group of other renderables? (Scene Graph's).
If we instead just make Renderables implement render(Renderer2D& r) interface. we can make each renderable pass the data it holds to the renderer without a hard defined interface.
