Pyxu v1.0.1

User-facing changes:

• Many improvements to HTML documentation.
• Move to full pip-based install process.
• Minor bug fixes to core library & extension mechanism.

Developer-facing changes:

• Update tox testenvs to avoid costly env setups (when unnecessary).
• Provide tox receipes to build PyPI packages & HTML docs.
• Replace setuptools with hatch as per PyPA guidelines.