We have TimingAuthor because we have karaokes made by people that are not users of karaberus (inactive/did not migrate, imported karaokes, ...). But we should associate Users to a TimingAuthor (already the case in the DB model) so we can add the timing author of the current user when uploading the subtitles, list issues assigned to our karaokes, ...

We'll probably still need some way to not set the author when doing minor changes to sub files.