Support also dates for TimePeriod's methods get_datetime_start/_end

See merge request !197

Resolve "Force __str__ methods to return strings"

Closes #151

See merge request !198

Update poetry.lock

See merge request !199

Update changelog from 2.0rc2

See merge request !195

(cherry picked from commit 869379e7)

Remove merge leftovers in changelog

See merge request !193

Drop usage of non-existing permission in permission rules for lesson substitutions

See merge request !192

Update poetry.lock

See merge request !190

Update the changelog from 2.0rc1

See merge request !189

(cherry picked from commit e039025b)

Resolve "Use correct semantic html elements"

Closes #146

See merge request !184

Resolve "Fix range check in next_lesson"

Closes #147

See merge request !185

This reverts commit a23a9462.

Translations update from Weblate

See merge request !174

Currently translated at 100.0% (127 of 127 strings)

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

Update translation files

See merge request !182

Resolve "Finally fix lessons_on_day property"

Closes #145

See merge request !183

# Conflicts:
#   CHANGELOG.rst

Resolve "Preference section is called Chronos"

Closes #144

See merge request !180

Fixup changelog chaos and set version to 2.0b2

See merge request !179

(cherry picked from commit 3f4ce4a7)

Resolve "Show abbreviations in the substitution plan only once"

Closes #140

See merge request !178