* feat(materialx): add bounded document reader and OpenPBR writer
* proof, video, latex, cms: satisfy the clippy lints that ship with Rust 1.100
The newer clippy flags needless bool guards and range loops whose index
only indexes one slice; express both with the equivalent iterators so
the workspace lint stays green on every platform.
* cms: index the ink loops instead of a range loop, which newer clippy rejects
* feat(materialx): resolve shader graphs and write OpenPBR materials
* feat(materialx): resolve shader graphs and write OpenPBR materials
