js cache: don't mess with global local/sessionStorage and use prefixed in cache, re #5205

git-svn-id: svn://develop.studip.de/studip/trunk@32900 c5b85792-5220-0410-ad23-ed5b6b8ad999
pagelayout: refine body element id generation, fixes #5208

git-svn-id: svn://develop.studip.de/studip/trunk@32901 c5b85792-5220-0410-ad23-ed5b6b8ad999