- Consistently use the variable CMAKE_BUILD_TYPE to select build type.
- Remove broken `doc_html` target.
- Remove swap files created by oldtest when cleaning.
- Only rerun `lintdoc` if any documentation files has changed.
Using CMAKE_INSTALL_PREFIX is unreliable as it's a cache variable,
meaning the users previous value will be used if not supplied. Instead,
use the `--prefix` flag which is guaranteed to always work.
Having to specify CI_BUILD for every CI job requires boilerplate. More
importantly, it's easy to forget to enable CI_BUILD, as seen by
8a20f9f98a. It's simpler to remember to
turn CI_BUILD off when a job errors instead of remembering that every
new job should have CI_BUILD on.
This will allow users to use AppImageUpdate to update their AppImage.
It requires publishing the created zsync file alongside the appimage
file for the releases.
