MAINT: Python <3.8 related cleanups

* DOC: use PR ref as version name in CircleCI preview

* DOC: style version button depending on release

* DOC: fix logic for switcher_version.

[skip actions] [skip azp] [skip travis]

* DOC: provision empty dataset attribute and simplify not.

[skip actions] [skip azp] [skip travis]

* added warning for axis=32

* corrected version to 1.23

* added tests for deprecation

* added newline EOF

* added newline EOF fix

* MAINT: Fixup deprecation text and add release note fragment

Co-authored-by: Sebastian Berg <sebastian@sipsolutions.net>

…and-comparison

API: Fix structured dtype cast-safety, promotion, and comparison

…/pandas (#21491)

* DOC: Add panel elements to index matching scipy/pandas.

* DOC: Update card styling in css to match scipy/pandas.

* DOC: Add release notes to nav bar.

* DOC: replace css in layout with html_css_files conf val.

* DOC: Fix page layout.

Co-authored-by: Stefan van der Walt <stefanv@berkeley.edu>

Co-authored-by: Stefan van der Walt <stefanv@berkeley.edu>

The PyArray_AsCArray API does not conform to the documentation and
document that the call steals a reference to the PyArray_Descr argument.

ENH: add ndenumerate specialization for masked arrays

Most of the removed info is already in the structured array dtype
doc or later in the release note - leave high-level summary in place.

ENH: Add 'keepdims' to 'average()' and 'ma.average()'.

ENH: Allow object and subarray dtypes in fromiter

[skip actions] [skip travis]

…some stuff in the NEP 50 draft...

MAINT,ENH: Rewrite scalar math logic

DOC: Add missing entries in `numpy.testing` documentation

Co-authored-by: Matti Picus <matti.picus@gmail.com>

* DOC: Windows and F2PY

* DOC:  Intel F2PY

* DOC: F2PY Windows Reviewer Comments I

Co-authored-by: Melissa Weber Mendonça <melissawm@gmail.com>

* DOC: Clean F2PY Win and add to index

* DOC: F2PY windows narrative rewrite

* DOC: Clean up Windows environment suggestions

* DOC: Add Windows Terminal Details

* DOC: Update windows index

* MAINT: Clean doc

* DOC: Add partials for Windows

* DOC: Update as per review

Co-authored-by: Melissa Weber Mendonça <melissawm@gmail.com>

* DOC,BLD: Add to toctree to appease build

Co-authored-by: Melissa Weber Mendonça <melissawm@gmail.com>

DOC: Update set of allowed f2cmap types

ENH: F2PY build output determinism

Co-authored-by: Ralf Gommers <ralf.gommers@gmail.com>
Co-authored-by: Pearu Peterson <pearu.peterson@gmail.com>
Co-authored-by: Melissa Weber Mendonça <melissawm@gmail.com>

I somewhat think the change for subclass logic is so esoteric, that I am
not even sure a release note is useful...

user/index is not an orphan page, it is references in the main index.rst
Unless there is another reason to mark it as orphan ?

Also lowercase a directive, it is the only instance of an uppercase
directive in all the source code of numpy/scipy.