The implementation of the standard domain so far has considered the
first child of the rubric node is the title of the rubric.  But it can
may multiple nodes when the rubric title is marked up.

This extracts the title of the rubric from the whole of the children
of it.

.. note::

   $ find sphinx tests LICENSE doc/conf.py -type f -exec sed -i '' -e 's/2007\-20../2007-2021/' {} \;
   $ git co sphinx/locale/**/*.js sphinx/templates/epub3/mimetype

Keep imports alphabetically sorted and their order homogeneous across
Python source files.

The isort project has more feature and is more active than the
flake8-import-order plugin.

Most issues caught were simply import ordering from the same module.
Where imports were purposefully placed out of order, tag with
isort:skip.