re #3835 Groupenumeration deleted + some bugfixes

git-svn-id: svn://develop.studip.de/studip/trunk@28709 c5b85792-5220-0410-ad23-ed5b6b8ad999
re #3835 bugfixes

git-svn-id: svn://develop.studip.de/studip/trunk@28711 c5b85792-5220-0410-ad23-ed5b6b8ad999