Set URLs for edit views in templates

Add choosen-js library and assets for nicer looking multiple select
Add new blocks for loading of individual assets to base template
Use choosen-js for multiple fields in AK submission view

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)

Resolve conflicts (AKSubmission views and translations)
Add merge migration
Fix owner slug migration for existing entries

currently only works when creating a new owner

Introduce i18n support to frontend

See merge request kif/akplanning!2

Improve AK categories

See merge request kif/akplanning!3

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

Add description to category model
Show tabbed list of different categories of AKs on submission overview

Adapt settings
Add i18n urls to central url conf
Add language chooser to base.html
Adapt readme and utils

create template for AK wish submission
create form for AK wish submission
create view for AK wish submission
adapt urls and buttons

Add TODOs for other data manipulation/auto-creation/...-tasks

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

exclude interest
exclude track

create form class
create template
configur urls
create submission view

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

allow AK owners to be empty
infer AK wish from empty owner list
show wish status in Admin overview

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

This message is used by the mixin to find the corresponding event for a slug

Create mixin (FilterByEventSlugMixin) to handle even slug parsing in generic views
Add submission url config
Include submission urls in central url config
Add index view for submissions

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

Create base.html
Add common template folder to settings

Resolve first partial task of #7

Basic design

See merge request kif/akplanning!1