~~~~~
Backwards incompatible.
Make the database schema more strict (identify data issues early, improve performance):
- add NOT NULL to columns where this was not enforces previously
- add UNIQUE constraints over column combinations where this was not enforced previously
For instructions on upgrading a present database see clld/db/schema_migrations/update_unique_null.py
Switch to using pytest for testing of clld as well as clld apps. Support for simpler
testing of apps has been moved to a pytest plugin pytest-clld.
Some obsolete functionality has been dropped.