[cleanup] Fix some flake8 errors
and drop upper bound of copyright along the way.
autoform module is not added to flake8-ok-files since there are some remaining
errors to be handled, but that's still a start.
.. _appobject_module:
:mod:`cubicweb.appobject`
=========================
.. automodule:: cubicweb.appobject
.. autoclass:: AppObject
:show-inheritance:
:members: