Two-sided BRDF and complex scene rendering

AdaPT now supports BRDF to be two-sided (but with the same attributes). With this we don't need to care about the normal direction given by modeling softwares (which might points inwards, causing primitive missing), so we can renderer highly complex scenes:

Kitchen scene (modeled by me via sketchup 2021 / blender)

Stuffs scene

All of the above scenes have their configuration file stored in scenes/cbox/, yet the obj model is not uploaded due to the line number and file sizes. These pictures are kept in gallery.md