Update dependency isort to v5

See merge request !60

Implement school term and validity range, remove photo cropping

See merge request !62

Resolve "Fix personal note filter id_ variable"

Closes #84

See merge request !59

Update copyright information

See merge request !58

Resolve "[Lesson view] Show summary (homework, etc.) of previous lessons"

Closes #29

See merge request !57

Resolve "Use base_print.html for full register print out"

Closes #76

See merge request !55

- Add extra templates for absences and tardinesses
- Add model extensions for lesson documentation and personal notes to LessonPeriod

Fix wrong offsets for weekdays

See merge request !54

Resolve "[Lesson view] Show buttons to go the previous/next lesson"

Closes #83

See merge request !56

Resolve "Show status icon for every lesson"

Closes #63

See merge request !50

Fix lint issues and reformat all files

See merge request !53

Resolve "Fix aggregation of absences and tardninesses"

Closes #75

See merge request !52

Review use of Materialize

Closes #61

See merge request !48

# Conflicts:
#	aleksis/apps/alsijil/templates/alsijil/week_view.html