This is `sphinx-quickstart` as modified to automatically produce
documentation for the module, taking a few hints from fonttools/ufoLib2
to inform structure, build workflow, and styling.

Having an explicit __all__ is necessary to avoid re-exporting objects
that we ourselves have imported (e.g. from the standard library).

This also helps avoid objects that this project did not author from
appearing in the automatically generated Sphinx documentation.

This list was generated by:

```python
import uharfbuzz
print(dir(uharfbuzz))
```

...before being manually pruned.

See harfbuzz#212

This is following the guidance at:

    https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html

...in preparation for adding Read the Docs build support, where having
an explicit requirements.txt file to point to will also be helpful.

This is based on the Sphinx reference config file here:

    https://docs.readthedocs.io/en/stable/config-file/v2.html#python-install

...with some trimming, customisation for the project, and additional
adjustments recommended for reproducible builds.