Furomon

- Another styling update sidebar-caption related changes in Sphinx.

- Add a basic domainindex page, without dedicated styling.
- Add recommendation for sphinx-opengraph.
- Account for newer Sphinx versions changing classes for captions.
- Account for the broken docutils release.
- Right align viewcode links (like `[source]`) allowing wrapping of API
signatures gradefully.

- Get `pygments_dark_style` working.
- Use the correct layout for domain index placeholder.

- Fix a typo in the README.
- Add an escape hatch for specific table of contents.

- Update Python-Requires to >=3.6.
- Account for nested admonitions.
- Center align items like other themes.
- Don't stylize the compound `kbd` tags.
- Fix a broken internal link in documentation.
- Fix a mistyped vertical-align style.
- Vertically align embedded-in-text images.
- Declare in HTML that the theme's pages support multiple color schemes.

- Fix a bug in how stylesheets are handled.
- Clarify how to install directly from GitHub.
- Document how to install from git.