[ticket/12143] Make it possible to use translated group names for non-special groups
* Elsensee/ticket/12143:
[ticket/12143] Fix tests after rebase
[ticket/12143] Avoid no output from get_group_name()
[ticket/12143] Fix those tests
[ticket/12143] Add some tests
[ticket/12143] Oops, fixed array index
[ticket/12143] Replace group name output
[ticket/12143] Add group helper class to translate groupnames
[ticket/12143] Add is_set method to language service