Gather info about mesh import

- Assimp. Supports .gltf, .blend, .fbx and a lot of other formats
    https://docs.rs/assimp/0.3.1/assimp/
        Last activity 4 years ago. Needs to be tested in practice to see if it works
    https://github.com/jkvargas/russimp
        Implementation seems to be thin and there's no crate, but the work is recent
- .blend
    https://crates.io/crates/blend
        Activity 2 years ago
        Does not support compressed .blend files and no writing of .blend files
        Looks like it is made by a single person
    Landon https://crates.io/crates/landon
- .gltf
    https://crates.io/crates/gltf
        Not a lot of recent activity but seems fine
        Used by bevy
- meshoptimizer and other
    Plexus https://plexus.rs/
        For computational geometry and polygonal mesh processing. It provides primitives, buffers, and graphs that are generic over their geometry and provide ergonomic geometric APIs for supported types
    Meshopt https://crates.io/crates/meshopt
        Vertex/index buffer optimization, cache friendly conversion, compression, stripify, efficiency analysis
        Didn't run out of the box
        No activity for 2 years
    Tesselation: https://crates.io/crates/tessellation
        Creates meshes out of functions
- USD
    https://crates.io/crates/usd
        Bindings. Pretty much the only option, early development, 2 contributors
legion-labs / legion

Gather info about mesh import #840
