remove expendable directory (name is now userfilter)

git-svn-id: svn://develop.studip.de/studip/trunk@29120 c5b85792-5220-0410-ad23-ed5b6b8ad999
re #4063
schei? encoding

git-svn-id: svn://develop.studip.de/studip/trunk@29121 c5b85792-5220-0410-ad23-ed5b6b8ad999
fix memory exhaustion on /course/{id}, refs #3484

git-svn-id: svn://develop.studip.de/studip/trunk@29122 c5b85792-5220-0410-ad23-ed5b6b8ad999