Extend 3ds Max file parser to be a standalone exporter

[kaetemi]

Extend 3ds Max file parser to be a standalone exporter.

For the 3D, skeleton, and animation data, export it into an intermediate format (GLTF or Blender) that can be imported to NeL format by Assimp.

NeL properties on nodes and NeL materials should be exported into a metadata file that is saved alongside the intermediate format. See the Assimp to NeL importer source code comments on how this will work.

See:

• https://github.com/ryzom/ryzomcore/tree/core4/nel/tools/3d/pipeline_max
• https://github.com/ryzom/ryzomcore/tree/core4/nel/tools/3d/pipeline_max_dump

[kaetemi]

(For landscape patch editing we will need a new standalone editor GUI as well.)

(And for scene editing an editor as well, maybe the same.)

[kaetemi]

Initial candidates are weapons and bot objects, since they don't have any animations or other complexity.

[kaetemi]

The goal is not to replace 3ds Max for authoring content, but to allow shifting to whichever is your preferred editor of choice.

It is a goal to remove 3ds Max as a requirement for building the assets, so only a subset of features will be permitted in max files.

The plugins for 3ds Max will also be deprecated for this, and a standalone tool for editing the material and properties metadata files should be built.

[kaetemi]

Example GUI for NeL material and property editor.

[kaetemi]

Texture selection widget with asynchronous loading and thumbnail caching is already somewhere in the code repository.