New Module: fixed precision math

[spmadden]

• Update top level irox module:
  • Update Cargo.toml
  • Update lib.rs
• Update top level README.md
• Update top level Cargo.toml/Cargo.lock
  • Ensure new module in main module list
  • Ensure new module dependency hotlink exists
• In the new module:
  • Used the templates in /dev/mod_template
  • Ensure README.md exists
  • Ensure CHANGELOG.md exists
  • Ensure Cargo.toml set up correctly
    • Ref: Crates.io Category Slugs
  • Ensure lib.rs/main.rs:
    • Marked with #![forbid(unsafe_code)]
    • Has main module docs
• Module released
  • verify just ci
  • cargo smart-release -u