Let there be light

And there was light!
For now there is no scene graph or property implementation, all lights are added in painter.cpp, check that out to see how you can add lights.
Yes, I haven't added that information, that should be the radiant intensity but without HDR this info would be meaningless, so for now it's just an artificial scale until HDR is implemented.
The direction can be expected to be normalized if you normalize them when creating the lights, i.e in painter.cpp.