Sphinx-theme-builder

- Include setuptools as a dependency.

- Add `stb npm` command, to make it easier to run npm within the nodeenv.
- Properly handle `nodeenv` and CLI colours.
- Get `node-version` from project configuration.
- Use the `node` from PATH, if it matches the required version
- Handle aborts coming out of click.
- Handle unclean exits in `build`.

- Improve `stb serve`.
- Improve handling and presentation of errors from `main`.
- Run project structure validation in more situations.
- Consolidate compiled asset calculation.
- Add a direct dependency on `nodeenv`.

- Update the paths that source assets are stored in.
- Correctly handle `[project]` in the error output.

Initial release.