Improve blank and unique constraints of model:
- allow blank starting times of slotes to store durations before scheduling and adapt string representation
- change unique constraint from name and shortname of AK to unique for each event only
Implement handling of tags for submission and update (auto-creation) by using a semicolon-separated text file instead of multiple choice field
Implement handling of durations for submission
Automatically generate short name
Use different forms for submission and update
Use special adapted template for AK updates instead of submission template
Fix EventSlugMixin for POST requests

Set URLs for edit views in templates

Introduce existing owner select field and dispatching views for POST submitted owner id
Adapt redirection flows
Adapt submission overview template
Introduce Owner edit view
Fix prepopulation issue in AKWish creation view (caused by inheritance)
Adapt template name to role as create and update template
Fix context issue for AK creation view (missing owner attribute)

Add visualization to ak list and detail page
Add option to treat them as an own category on submission overview

Add template and template tag for messages
Adapt success url of AK creation to point to detail page of created AK and show success message

Created filter to represent values using fontawesome icons
Added template tags (and corresponding templates) for category and tag lists and badges
Adapted existing view templates to use these tags
Fixed presentation of AK indicator

avoid clashes with python keyword

Add dynamic title handling to base html
Add more information to submission overview
Move AK list to own file for use in other pages
Add detail view for AK
Add views with AK overview list as well as filtered lists (by type and tag)
Add corresponding German translations

Create html template
Add translation
Add property for easy access to list of AK owners to AK model