(cherry picked from commit 82b30f36cb)
82b30f36cb
Last step of the migration from Travis/AppVeyor to GitHub Actions. `werror=yes` should be enabled once outstanding warnings have been fixed.
master
Removes AppVeyor and all Travis jobs but the iOS one, which hasn't been ported to GitHub Actions yet (should be done soon). Backports new style scripts from `master` branch too to do the same checks.