* Basic functionality
* API
* Do not delete seats with vouchers
* Show seat in list of seats
* Validate availability of seats
* Fix invalid logic in Seat.is_available
* Show voucher name in edit form
* Allow filtern events-ressource on API by attrs
* Document meta-data attr-filter for order resource
* Actually document the change and not some random other nonsensical thing...
* Doc for subevent-filtering
* Test for attr-filtering on events resource
* Allow attr-filtering on subevents
* Add attr-filter test for subevent
* Update doc/api/resources/subevents.rst
* Update src/tests/api/test_subevents.py
* Update doc/api/resources/events.rst
* 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
* 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
* Change semantics of changing orders
This basically does two things to the "Change products" view of orders and the
OrderChangeManager program API:
1) It decouples changing items or subevents from changing prices.
OrderChangeManager.change_item() and .change_subevent() no longer
touch the price of a position. Instead .change_price() needs to be
called explicitly. However, a client-side JavaScript component now
*proposes* a new price based on the changed item or subevent.
2) The user interface now exposes the possibility of doing multiple
things at the same time, i.e. changing the item, subevent and price
in the same operation. OrderChangeManager already allowed this
before.
(1) is basically a consequence of (2), while (2) is a prerequesite for
e.g. the `seating` branch, where changing the subevent will always
require changing the seat.
* Add tests for price calculation API
* Upgrade django and stuff
* Update to Django 2.2 and recent versions of similar packages
* Provide explicit orderings to all models used in paginated queries
* Resolve naive datetime warnings in test suite
* Deal with deprecation warnings
* Fix sqlparse version
* Data model + Editor
* Cart and order management
* Rebase migrations
* Fix typos, add tests on cart handling
* Add tests for checkout and quotas
* Add API endpoints
* Validation of settings
* Front page tax display
* Voucher handling
* Widget foo
* Show correct net pricing
* Front page tests
* reverse charge foo
* Allow to require bundling
* Fix test failure on postgres
- [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

- [x] Data model
- [x] display in order view in backend
- [x] review all usages of OrderPositions.objects
- [x] review all usages of order.positions
- [x] review all other model usages
- [x] review plugins
- [x] plugins backwards-compatible API?
- [x] decide on way forward for REST API
- [x] need to cancel fees
- [x] tests
- [ ] plugins
- [ ] gdpr
- [ ] reports
- [x] docs