* 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
* Send signal when orderposition is checked in
* Add position_checked_in signal to documentation
* Rename signal to checkin_created
* Update general.rst
* Update signals.py
Co-authored-by: Raphael Michel <mail@raphaelmichel.de>
* Allow to import orders
* seats, subevents
* Plugin support
* Add docs
* Warn about lack of quota handling
* Control interface test
* Test skeleton
* First tests for the impotr columns
* Add tests for all columns
* Fix question validation
* 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!
* Initial work on seating
* Add seat guids
* Add product_list_top
* CartAdd: Ignore item when a seat is passed
* Cart display
* product_list_top → render_seating_plan
* Render seating plan in voucher redemption
* Fix failing tests
* Add tests for extending cart positions with seats
* Add subevent_forms to docs
* Update schema, migrations
* Dealing with expired orders
* steps to order change
* Change order positions
* Allow to add seats
* tests for ocm
* Fix things after rebase
* Seating plans API
* Add more tests for cart behaviour
* Widget support
* Adjust widget tests
* Re-enable CSP
* Update schema
* Api: position.seat
* Add guid to word list
* API: (sub)event.seating_plan
* Vali fixes
* Fix api
* Fix reference in test
* Fix test for real
* .
* Add a position detail page to the frontend
* Mail templates
* Send mails
* Send reminder email
* Add position support to sendmail plugin
* Add and fix some tests
* Fix failing test on real databases
- [x] Provide data model and configuration toggle
- [x] Allow to delete individual test orders
- [x] Add tests
- [x] Add a prominent warning message to the backend if test mode orders exist (even though test mode is off), as this leads to wrong statistics
- [x] Decide if and how to generate invoices for test orders as invoice numbers cannot be repeated or should not have gaps.
- [x] Decide if and how we expose test orders through the API, since our difference pull mechanism relies on the fact that orders cannot be deleted.
- [x] Decide if and how we want to couple test modes of payment providers?
- [ ] pretix.eu: Ignore test orders for billing
- [ ] Adjust payment providers: Mollie, bitpay, cash, fakepayment, sepadebit

* Custom HTML email renderers
* Move inline_css call
* Small fixes
* New HTML mail style for pretix
* Thumbs
* Inlinestyle for notifications
* Documentation
* Set line-height