Hist

* Stacks support axes, math operations, projection, setting items, and
iter/dict construction. They also support histogram titles in
legends. Added histoprint support for Stacks.
[291](https://github.com/scikit-hep/hist/pull/291)
[315](https://github.com/scikit-hep/hist/pull/315)
[317](https://github.com/scikit-hep/hist/pull/317)
[318](https://github.com/scikit-hep/hist/pull/318)

* Added `name=` and `label=` to histograms, include Hist arguments in
QuickConstruct. [297](https://github.com/scikit-hep/hist/pull/297)

* AxesTuple now supports bulk name setting,
`h.axes.name = ("a", "b", ...)`.
[288](https://github.com/scikit-hep/hist/pull/288)

* Added `hist.new` alias for `hist.Hist.new`.
[296](https://github.com/scikit-hep/hist/pull/296)

* Added `"efficiency"` `uncertainty_type` option for `ratio_plot` API.
[266](https://github.com/scikit-hep/hist/pull/266)
[278](https://github.com/scikit-hep/hist/pull/278)

Smaller features or fixes:

* Dropped Python 3.6 support.
[194](https://github.com/scikit-hep/hist/pull/194)
* Uses boost-histogram 1.2.x series, includes all features and fixes,
and Python 3.10 support.
* No longer require scipy or iminuit unless actually needed.
[316](https://github.com/scikit-hep/hist/pull/316)
* Improve and clarify treatment of confidence intervals in `intervals`
submodule.
[281](https://github.com/scikit-hep/hist/pull/281)
* Use NumPy 1.21 for static typing.
[285](https://github.com/scikit-hep/hist/pull/285)
* Support running tests without plotting requirements.
[321](https://github.com/scikit-hep/hist/pull/321)

* Support `.stack(axis)` and stacked histograms.
[244](https://github.com/scikit-hep/hist/pull/244)
[257](https://github.com/scikit-hep/hist/pull/257)
[258](https://github.com/scikit-hep/hist/pull/258)
* Support selection lists (experimental with boost-histogram 1.1.0).
[255](https://github.com/scikit-hep/hist/pull/255)
* Support full names for QuickConstruct, and support mistaken usage in
constructor. [256](https://github.com/scikit-hep/hist/pull/256)
* Add `.sort(axis)` for quickly sorting a categorical axis.
[243](https://github.com/scikit-hep/hist/pull/243)

Smaller features or fixes:

* Support nox for easier contributor setup.
[228](https://github.com/scikit-hep/hist/pull/228)
* Better name axis error.
[232](https://github.com/scikit-hep/hist/pull/232)
* Fix for issue plotting size 0 axes.
[238](https://github.com/scikit-hep/hist/pull/238)
* Fix issues with repr information missing.
[241](https://github.com/scikit-hep/hist/pull/241)
* Fix issues with wrong plot shortcut being triggered by Integer axes.
[247](https://github.com/scikit-hep/hist/pull/247)
* Warn and better error if overlapping keyword used as axis name.
[250](https://github.com/scikit-hep/hist/pull/250)

Along with lots of smaller docs updates.

* Add `plot_ratio` to the public API, which allows for making ratio
plots between the histogram and either another histogram or a
callable. [161](https://github.com/scikit-hep/hist/pull/161)
* Add `.profile` to compute a (N-1)D profile histogram.
[160](https://github.com/scikit-hep/hist/pull/160)
* Support plot1d / plot on Histograms with a categorical axis.
[174](https://github.com/scikit-hep/hist/pull/174)
* Add frequentist coverage interval support in the `intervals` module.
[176](https://github.com/scikit-hep/hist/pull/176)
* Allow `plot_pull` to take a more generic callable or a string as a
fitting function. Introduce an option to perform a likelihood fit.
Write fit parameters' values and uncertainties in the legend.
[149](https://github.com/scikit-hep/hist/pull/149)
* Add `fit_fmt=` to `plot_pull` to control display of fit params.
[168](https://github.com/scikit-hep/hist/pull/168)
* Support `<prefix>_kw` arguments for setting each axis in plotting.
[193](https://github.com/scikit-hep/hist/pull/193)
* Cleaner IPython completion for Python 3.7+.
[179](https://github.com/scikit-hep/hist/pull/179)

* Fix bug with `plot_pull` missing a sqrt.
[150](https://github.com/scikit-hep/hist/pull/150)
* Fix static typing with ellipses.
[145](https://github.com/scikit-hep/hist/pull/145)
* Require boost-histogram 1.0.1+, fixing typing related issues,
allowing subclassing Hist without a family and including a important
Mean/WeighedMean summing fix.
[151](https://github.com/scikit-hep/hist/pull/151)

* Support boost-histogram 1.0. Better plain reprs. Full Static Typing.
[137](https://github.com/scikit-hep/hist/pull/137)
* Support `data=` when construction a histogram to copy in initial
data. [142](https://github.com/scikit-hep/hist/pull/142)
* Support `Hist.from_columns`, for simple conversion of DataFrames and
similar structures
[140](https://github.com/scikit-hep/hist/pull/140)
* Support `.plot_pie` for quick pie plots
[140](https://github.com/scikit-hep/hist/pull/140)

* Fix density (and density based previews)
[134](https://github.com/scikit-hep/hist/pull/134)