v1.0.18

Automated release built by maturin.

• PyPI carries the slim wheels (~2 MB, no bundled
  language-detection models) plus the source distribution.
• The full wheels attached here embed the lingua-rs models
  (~140 MB) so num2words_sentence(lang=None) auto-detects
  natively. Install one with pip install <asset-url>.

What's Changed

• docs: add comprehensive REFERENCE.md + refresh README by @jqueguiner in #118
• ci: auto-purge camo cache on release so README badges refresh by @jqueguiner in #119
• Port conversion engine to Rust; Python becomes a thin binder by @jqueguiner in #122
• release: use PYPI_API_TOKEN for PyPI publish by @jqueguiner in #123
• Bump version to 1.0.11 by @jqueguiner in #124
• Bump version to 1.0.18 by @jqueguiner in #125

Full Changelog: v1.0.17...v1.0.18