helpbar: refine opening/closing of helpbar; byebye hover, hello clicking; mobile and desktop friendly as well as intuitive (hopefully), re #3768

git-svn-id: svn://develop.studip.de/studip/trunk@31057 c5b85792-5220-0410-ad23-ed5b6b8ad999
wiki: fix revision history regarding deleted users, fixes #4488

git-svn-id: svn://develop.studip.de/studip/trunk@31058 c5b85792-5220-0410-ad23-ed5b6b8ad999