Merge branch 'master' into 91-add-task-for-checking-plausibility-of-data

aleksis/apps/alsijil/data_checks.py

aleksis/apps/alsijil/forms.py

aleksis/apps/alsijil/locale/ar/LC_MESSAGES/django.po

aleksis/apps/alsijil/locale/de_DE/LC_MESSAGES/django.po

aleksis/apps/alsijil/locale/fr/LC_MESSAGES/django.po

aleksis/apps/alsijil/locale/la/LC_MESSAGES/django.po

aleksis/apps/alsijil/locale/nb_NO/LC_MESSAGES/django.po

aleksis/apps/alsijil/locale/tr_TR/LC_MESSAGES/django.po

aleksis/apps/alsijil/managers.py

aleksis/apps/alsijil/menus.py

aleksis/apps/alsijil/model_extensions.py

aleksis/apps/alsijil/models.py

aleksis/apps/alsijil/preferences.py

aleksis/apps/alsijil/rules.py

aleksis/apps/alsijil/static/css/alsijil/alsijil.css

aleksis/apps/alsijil/static/css/alsijil/lesson.css

aleksis/apps/alsijil/tables.py

...sis/apps/alsijil/templates/alsijil/absences/register.html

...apps/alsijil/templates/alsijil/class_register/groups.html

...apps/alsijil/templates/alsijil/class_register/lesson.html