Merge branch 'master' into 260-add-personal-note-management-dialog-in-course-book

# Conflicts:
#	aleksis/apps/alsijil/frontend/components/coursebook/Coursebook.vue
#	aleksis/apps/alsijil/frontend/components/coursebook/CoursebookDay.vue
#	aleksis/apps/alsijil/frontend/components/coursebook/absences/ManageStudentsDialog.vue
#	aleksis/apps/alsijil/frontend/components/coursebook/absences/ManageStudentsTrigger.vue
#	aleksis/apps/alsijil/frontend/components/coursebook/absences/participationStatus.graphql
#	aleksis/apps/alsijil/frontend/components/coursebook/coursebook.graphql
#	aleksis/apps/alsijil/frontend/components/coursebook/documentation/LessonNotes.vue
#	aleksis/apps/alsijil/frontend/messages/de.json
#	aleksis/apps/alsijil/models.py
#	aleksis/apps/alsijil/schema/__init__.py
#	aleksis/apps/alsijil/schema/documentation.py
#	aleksis/apps/alsijil/schema/participation_status.py