Title: MLT renderer : has made some progress.

The Cornell box scene will delete those highlights after the test. But in the end, the light source looks right. The next project (:1) has some support for spectral rendering. It is based on PBRT. Just figure out how to achieve it. 2) The physics-based sky model of Sunlight Sky Model Preetham, Shirley and Smits. Maxwell Render and Indigo both use this model. Very real skylight, especially when combined with spectral rendering! 3) In order to improve the rendering time, distributed rendering must be parallelized, and jobs can be distributed to some remote machines, such as rendering fields. Update of Sponza scene (rendering time is about 6 or 7 hours)