Update translation files

See merge request !201

Resolve ""Lesson documentation" tab missing in 'My overview' for teachers"

Closes #166

See merge request !202

Resolve "Preference section is German"

Closes #167

See merge request !200

Update maintainers and Trove categorisation

See merge request !198

Set version and core dependency to 2.0b0

See merge request !196

Resolve "Fields must be unique per site"

Closes #163

See merge request !197

Resolve "Update feature list"

Closes #164

See merge request !194

Resolve "Fix rules/permissions"

Closes #165

See merge request !195

Update changelog for 2.0b0

See merge request !192

Translations update from Weblate

See merge request !193

Currently translated at 100.0% (250 of 250 strings)

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

Resolve "Rename rules to allow differentiation from permissions"

Closes #161

See merge request !190

Resolve "Sync Copyright in README.md and apps.py"

Closes #162

See merge request !191

Resolve "Update copyright"

Closes #160

See merge request !189

Merge branch '115-person-overview-implement-multiple-selection-for-marking-absences-as-excused-or-for-deleting' into 'master'

Resolve "[Person overview] Implement multiple selection for marking absences as excused or for deleting"

Closes #121 und #115

See merge request !111

Merge branch '157-permission-checking-decorators-raise-internal-server-error-if-the-user-is-anonymous' into 'master'

Resolve "Permission checking decorators raise internal server error if the user is anonymous"

Closes #157

See merge request !188