- Update database models to the new declarative mapping syntax See https://docs.sqlalchemy.org/en/20/orm/mapping_styles.html#orm-declarative-mapping - Make use of Flask-SQLAlchemy to manage database connections - Remove cli command interface in favor of just deleting the sqlite file and reseeding when no tables are detected. - Add list of iso639_1 language codes and names, and add to seed list - Other changes to file structure.