* Upgrade Django to 3.0 and other dependencies to recent versions
* Fix otp version contsraint
* Remove six dependency
* Resolve some warnings
* Fix failing tests
* Update django-countries
* Resolve all RemovedInDjango31Warnings in test suite
* Run isort
* Fix import
* Update PostgreSQL version on travis
* Drop support for maindomain_urls/subdomain_urls in plugins
* Allow to use a custom domain per event
* Fix bug when manually saving domains
* Fix custom domains in debugging
* Fix middleware
* Fix middleware again, update docs
* Fix caching issues in SASS compilation
* Allow to set a custom page background color
* Allow to disable round corners
* Support larger header pictures
* Allow to show title despite header
* Move language picker
* FIx widget styles
* PoC for ItemMetaProperties/Values
* Missing is_valid
* ItemMetaProperties/Values in editable via API, cloneable
* Tests
* Add Docs
* Fix import order
* Fix another import sorting...
* Typeahead for ItemMetaValues
* Test for editing event-objects
* Fix typeahead permission checks
* Further access restriction
Co-authored-by: Raphael Michel <mail@raphaelmichel.de>
* Remove check password for event deletion, instead require recent login.
* Reauthenticate for backends using authentication_url.
* Require recent login for data shredder and prompt slug instead of password.
* Fix tests for recent login required on event delete and data shred.
* Pull request remarks for recent login required for event delete and data shred.
* Remove unused imported check_password.
* TicketOutput-Providers: Make preview optional; download/attachable optional; optional specific target; update doc
* Spelling fixes in doc
* Changes after code-review
* Changes after code-review
* Commit missing template file
* Allow for redirects instead of files
* Return HTTPResponse with Content-Type text/uri-list on API
* Update API-doc
* Add viewable to spellinglist, fixing doc-test
* First tabs
* Convert more pages
* Convert question page
* Item form
* Add item_formsets signal
* Revert "Add new signal nav_item"
This reverts commit 1ce613ff89.
* Formset is a word!