unrequire glfw

ok, now that I've been able to get this running, I'd like the option to provide an opengl context of my own!

(and honestly I have no use for AntTweakBar)

I'd prefer something that mimicked the browser window object which I've been attempting to do in [tmpvar/glfw3-window](https://github.com/tmpvar/glfw3-window/) - being able to use this in conjunction with that would make me super happy.