svg: merge dev branch for svg icons into trunk, re #5007

git-svn-id: svn://develop.studip.de/studip/trunk@32212 c5b85792-5220-0410-ad23-ed5b6b8ad999
svg: use svg for helpbar icon as well, re #5007

git-svn-id: svn://develop.studip.de/studip/trunk@32214 c5b85792-5220-0410-ad23-ed5b6b8ad999
use correct dimensions for logo on index_nobody, fixes #5008

git-svn-id: svn://develop.studip.de/studip/trunk@32215 c5b85792-5220-0410-ad23-ed5b6b8ad999