Resolve "Make previous/next lesson buttons independent of validity range"

Closes #105

See merge request !114

Currently translated at 100.0% (122 of 122 strings)

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

Fix issues according to absences admin

See merge request !108

Resolve "Show only the parent groups in 'Affected groups'"

Closes #95

See merge request !111

Merge branch '100-sort-the-list-by-parent-groups-if-displaying-parent-groups-is-activated' into 'master'

Resolve "Sort the list by parent groups if displaying parent groups is activated"

Closes #100

See merge request !110

Resolve "Sort teacher abbreviations alphabetically"

Closes #103

See merge request !109

Fix missing returns and assignments in relation to supervision querysets

See merge request !107

Update lockfile

See merge request !106

Resolve "Summarise double lessons"

Closes #97

See merge request !105

Make lint clean

See merge request !104

Show substitution comment on all plans independent of any extra conditions

See merge request !103

Use setuptools entrypoint to register app

See merge request !102

Enable PyPI build and reformat

See merge request !100

Order teachers, groups and rooms on timetable overview alphabetically

See merge request !98