rewrite the mesh functions

Rewrite the mesh functions entirely, support multiple materials, add support for material Ids, fix the crash of empty material Ids, and support all material IDs as long as it's not the end of the material Ids list.

Add support for shadowtransparent

Add support for shadowtransparent and shadow catcher option

Caustic test scene

Caustic test scene

Merge branch 'master' of https://github.com/LuxCoreRender/MaxLuxCore

Update README.md

Update README.md

Update README.md

Fix material category

Add Math Map and fix map category, bug fix, check if material is supported by renderer.

Fix for incorectly remove first texture in scene

Fix for incorectly remove first texture in scene, wrong glass parameter and crash on map with middle east characters