Merge branch '211-implement-vue-substitution-frontend' into engs-4.0

...is/apps/chronos/frontend/components/LessonEventOldNew.vue

...s/apps/chronos/frontend/components/LessonEventSubject.vue

aleksis/apps/chronos/frontend/components/NoTimetableCard.vue

aleksis/apps/chronos/frontend/components/SelectTimetable.vue

aleksis/apps/chronos/frontend/components/Timetable.vue

aleksis/apps/chronos/frontend/components/amendLesson.graphql

...ntend/components/calendar_feeds/details/LessonDetails.vue

aleksis/apps/chronos/frontend/components/timetableTypes.js

aleksis/apps/chronos/frontend/messages/de.json

aleksis/apps/chronos/frontend/messages/en.json

aleksis/apps/chronos/models.py

aleksis/apps/chronos/schema/__init__.py

...is/apps/chronos/templates/chronos/partials/subs/room.html