TODO:

Materials :
	_ load saved material
	_ material library
	_ slope map editor

Interface :
	_ fix scaling / rotation bug
	_ new povray frontend class
	_ OpenGL selection ( mouse )
	_ undo / redo
	_ plugins interface
	_ NLS

Objects :
	_ create :
		_ plan
		_ spotlight
		_ cylinder
	_ save / load objects
	_ cut / copy / paste
	_ CSG objects
	_ all the others ...
	_ mesh manipulation tools ...

Scene :
	_ load / save scene
	_ add atmospheric effects : media, fog, sky sphere, rainbow...
	_ global settings