Flox

Many bugfixes thanks to reports by aulemahal

What's Changed
* Add upstream-dev test by dcherian in https://github.com/dcherian/flox/pull/93
* Add hourly climatology story by dcherian in https://github.com/dcherian/flox/pull/97
* Fix mixing of blockwise and map-reduce strategies. by dcherian in https://github.com/dcherian/flox/pull/103
* Fix reductions on boolean reductions. by dcherian in https://github.com/dcherian/flox/pull/104
* Use isnull instead of isnan: engine="flox" by dcherian in https://github.com/dcherian/flox/pull/105


**Full Changelog**: https://github.com/dcherian/flox/compare/v0.5.1...v0.5.2

What's Changed
* Add py.typed by Illviljan in https://github.com/dcherian/flox/pull/92
* Fix binning with "cohorts" & "split-reduce" by dcherian in https://github.com/dcherian/flox/pull/94

New Contributors
* Illviljan made their first contribution in https://github.com/dcherian/flox/pull/92

**Full Changelog**: https://github.com/dcherian/flox/compare/v0.5.0...v0.5.1

- Minor bugfixes
- Add Aggregation as a top-level import
- Improve Aggregation docs.

- Grouping by multiple variables
- New kwarg `reindex` to duplicate the xhistogram approach

- Add `reindex` kwarg