Merge branch 'release-5.21'

New release version 5.20

New release version 5.20

Merge branch 'release-5.19'

Merge branch 'release-5.18'

Issue template updated

Merge conflicts that should not have happened

Last release was apparently not done according to my guide

Merge branch 'release-5.15'

Merge branch 'release-5.14'

Bugfixing release