Prepare docs/ for Sphinx

- Rename doc -> docs
- Remove epydoc config
- Add Sphinx makefiles
- Copy and modify Translate Toolkit Sphinx conf
- Add themes submodule
- Ignore _build/
Convert Dokuwiki pages to reStructureText

- Used wiki2rst for raw conversion
- Rewrap text
- Removed obsolete files
- Fixed table conversion
- Fixed doc cross-reference headers
- Fix image links
- Add :wp: external link
- Add TOC
Correct links

- Correct Intersphinx links
- Avoid inherited link text
- Fix, update, delete external links and reword text as needed
- Reword links with duplicated link text
- Correct https redirects
Use versionadded

- .. versionadded:: N.N
- Reword text to remove version references
Stylistic fixes

- Change headings to Title Case
- Use em-dash
Minor post migration fixes

- Broken URL
- Bullet list
- Cleaner cross-ref link
Add favicon for docs
Documentation link fixes

External
- Create :wiki: extlink for remaining wiki docs
- Use :wp: extlink
- Fix some broken :wp: links

Use own link text to prevent strange page header text appearing for
links.
Add ignore for linkcheck
Remove version info in text
Improve documentation formatting

- Use :menuselection:, :kbd: and :envvar: markers
- Correct code highlighting format
- Use inline text when needed
- Convert list to more readable table
Highlight setting names and files