Merge branch 'master' into feature/performance-optimizations

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

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

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

...apps/alsijil/templates/alsijil/class_register/person.html

...s/alsijil/templates/alsijil/class_register/week_view.html

...lsijil/templates/alsijil/partials/lesson_status_icon.html

aleksis/apps/alsijil/templatetags/__init__.py

aleksis/apps/alsijil/templatetags/time_helpers.py