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.
(1) fragColor is directly manipulated .. later on i would change this and only set fragColor once in the end
(2) there seems to be no handling of ranges here.. is this already preparing for HDR? then this should be commented and for HDR as stated above, a consistent usage of units for intensity values would be nice.