Indexed material

Main addition

Adding the support of using several materials, indexed, on a same mesh using:

• per-face indices
• a texture to map the indices

Side contribution

Adding the support of UTIA materials, with a variety of supported parameterization. Also, starting a refactor on handling measured materials in Malia (no impact on existing materials yet).

TODO

Complete the documentation for UTIA.

Internal modification

Each material is now fully compiled and directly attached to its belonging shape. A lambert proxy is no longer used.

Limitation

Current limitation: meshes with indexed materials do not exploit RTCores.