fixes #4544, set schedule read-only if rendered in widget

git-svn-id: svn://develop.studip.de/studip/trunk@31540 c5b85792-5220-0410-ad23-ed5b6b8ad999
refs #4544, set correct default for days

git-svn-id: svn://develop.studip.de/studip/trunk@31541 c5b85792-5220-0410-ad23-ed5b6b8ad999