.. 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.

Signed-off-by: oleg.hoefling <oleg.hoefling@gmail.com>

Signed-off-by: oleg.hoefling <oleg.hoefling@gmail.com>

Signed-off-by: oleg.hoefling <oleg.hoefling@gmail.com>

Signed-off-by: oleg.hoefling <oleg.hoefling@gmail.com>

This postpones the evaluation of LaTeX packages via
``app.add_latex_package()`` to just before writing .tex file.  That
allows extensions to add LaTeX packages during reading and resolving
phase.