Datasette-dateutil

- The `dateutil_parse()`, `dateutil_parse_fuzzy()`, `dateutil_parse_dayfirst()` and `dateutil_parse_fuzzy_dayfirst()` functions all now accept an optional second argument specifying a "default" datetime to consider if some of the details are missing. [5](https://github.com/simonw/datasette-dateutil/issues/5)

- Documentation showing how to use these functions in conjunction with `json_each()` to join against other tables. 2

- New `dateutil_rrule()` and `dateutil_rrule_date()` SQL functions. 1
- New `dateutil_dates_between()` SQL function. 1

- Initial release.