- Refactor fog in a new 'atmosphere' module.
- In GUI, revertConfig should lock the previews while reverting.
- All Save and Load methods should have same signature : void ...Save(FILE*, ...*)
- All noises should use the same entropy pool (saved separately), and avoid reallocs.
- Remove all global variables (render_quality, render_width...), it should all be set in Renderer.
- Make multi-lights work, to restore lighting from skydome.