Add CI

The CI builds, tags, create a release and a generic pages and finally publishes to Gitlab pages automatically. For development branches, it will only build.

requested review from @HugoTrentesaux

requested review from @moul and removed review request for @HugoTrentesaux

removed review request for @moul

No idea how to add 2 people as reviewers.. So ping @moul and @HugoTrentesaux

approved this merge request

added 2 commits

• a2c79c49 - 1 commit from branch websites:master
• 5ae1296a - Add CI

Compare with previous version

merged