rss feeds: adjust table layout to new conditions, fixes #4168

git-svn-id: svn://develop.studip.de/studip/trunk@29335 c5b85792-5220-0410-ad23-ed5b6b8ad999
rss feeds: display info messagebox instead of table layout, fixes #4177

git-svn-id: svn://develop.studip.de/studip/trunk@29336 c5b85792-5220-0410-ad23-ed5b6b8ad999
prevent xss fixes #4175

git-svn-id: svn://develop.studip.de/studip/trunk@29337 c5b85792-5220-0410-ad23-ed5b6b8ad999