Drop python2 support
This mostly consists in removing the dependency on "six" and updating
the code to use only Python3 idioms.
Notice that we previously used TemporaryDirectory from
cubicweb.devtools.testlib for compatibility with Python2. We now
directly import it from tempfile.
Base views
----------
|cubicweb| provides a lot of standard views, that can be found in
:mod:`cubicweb.web.views` sub-modules.
A certain number of views are used to build the web interface, which apply to one
or more entities. As other appobjects, their identifier is what distinguish them
from each others. The most generic ones, found in
:mod:`cubicweb.web.views.baseviews`, are described below.
You'll probably want to customize one or more of the described views which are
default, generic, implementations.
.. automodule:: cubicweb.web.views.baseviews
You will also find modules providing some specific services:
.. automodule:: cubicweb.web.views.navigation