merge 3.20.9 into 3.21
Fix conflict in unittest_postgres.py by changing sources configuration
in PostgresTimeoutConfiguration.__init__ so it happens *after*
setUpModule().
Add some entities
-----------------
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.