CI: GitHub Actions

[tueda]

Github Actions offer free 20 concurrent jobs , while Travis CI offers 5. Maybe some of the current CI jobs (for example Valgrind-related jobs), or all of them, could be moved from Google (Travis CI backbone) to Microsoft (GitHub Actions backbone), which gives us a speed gain in CI.

It is also possible to automatize generating documentation on GitHub.

[tueda]

Now, travis-ci.org has been shut down...

[tueda]

I have set up GitHub Actions with 2 workflows. Test is for building and testing with measuring code coverage to be uploaded to coveralls.io. Deploy is for building binaries and generating manuals, which will be published to GitHub Releases when the commit has a versioning tag starting with v, for example, v4.2.2 or v5.0.0.

Some notes:

• Currently, many tests fail due to #412.
• The Deploy workflow contains code to build native Windows binaries but is now disabled because of too many test failures, which need some investigation.
• Binaries are built with Ubuntu 18.04 and macOS 10.15 images, the oldest versions available that hopefully maximize compatibility, but they are deprecated. If we want to release a patch version, it may be good to do it before their deprecation.
  • https://github.com/actions/runner-images/issues/6002
  • https://github.com/actions/runner-images/issues/5583
• To install Ubuntu packages, I found https://github.com/awalsh128/cache-apt-pkgs-action very helpful. Unfortunately, it doesn't work with LaTeX packages: https://github.com/awalsh128/cache-apt-pkgs-action/issues/57.
• In the old Travis-CI setup, more tests were available: i386 (added in 7c9706cc5e5eee3b0c8ab85d2ac78c4fcaf6ee21), sanitizers, forcer (added in d659e9e902de5721abac42be8fadf28686644118) and clang. Currently, they are not in this GitHub Actions setup.

In the next commit, I will remove the remaining files related to Travis CI and close this issue.