Merge branch '304-make-person-select-in-long-term-absence-dialog-filterable-by-adding-a-preference-for-the-group' into 'master'

Resolve "Make person select in long term absence dialog filterable by adding a preference for the group type for which ownership is required"

Closes #304

See merge request !386

Merge branch '299-move-action-buttons-in-multiple-selection-of-persons-in-lesson-to-the-footer-of-the-card' into 'master'

Resolve "Move action buttons in multiple selection of persons in lesson to the footer of the card"

Closes #299

See merge request !385

Add close button to dialogs

See merge request !384

Resolve "Search of student names in absence management dialog doesn't work"

Closes #292

See merge request !381

Translations update from Weblate

See merge request !379

Translations update from Weblate

See merge request !377

Currently translated at 100.0% (315 of 315 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil/de/

Currently translated at 100.0% (66 of 66 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/de/

Currently translated at 20.0% (12 of 60 strings)

Translation: AlekSIS/AlekSIS-App-Alsijil-Frontend
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-alsijil-frontend/uk/

Update translation messages

See merge request !378

Add dialog for creation of long-term absences

Closes #265

See merge request !356

Fix filter for groups and courses to show the right data

See merge request !374

Resolve "Improve displaying of events without course/subject"

Closes #294

See merge request !376

Resolve "Add personal note management dialog in course book"

Closes #260, #263, and #273

See merge request !362

- only within current school term
- no duplicates
- unique ID for every element

Merge branch '260-add-personal-note-management-dialog-in-course-book' of edugit.org:AlekSIS/official/AlekSIS-App-Alsijil into 260-add-personal-note-management-dialog-in-course-book

Fix design for cancelled lessons and don't allow participation status with cancelled lessons

See merge request !371

Update copyright

See merge request !372