- Add `sphinx.ext.extlinks` extension, and use for repetetive links
- Conditionally enable `sphinx_copybutton` if found
- Wrap inline literals with double \` pairs, to format monospaced
- Turn developer page OS note into a Warning box, and replace the
outdated PDF install instructions link with links to the Windows
and Mac build instructions in the libopenshot project wiki
- Wrap paragraphs at periods or commas (sentence-per-line) instead of
arbitrarily fitting to a certain width
- Use shorter sentences where possible
