Test and fix "pickleability" of Binary objects
which has been recently broken while some cubes rely on this (eg fastimport).
Do some licensing/pep8 cleanup along the way.
Closes #13385274
Add some entities
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As manager, you can access to entity creation forms by using the `site management`_ page.
.. _`site management`: ../manage
As regular user, the index page or the action box may propose some links to create entities according to the context.