[web] removed unused imports in basecomponents

[test] Depends on psycopg2-binary Avoids the following warning: The psycopg2 wheel package will be renamed from release 2.8; in order to keep installing from binary please use "pip install psycopg2-binary" instead. For details see: <http://initd.org/psycopg/docs/install.html#binary-install-from-pypi

[doc/changelog] the removal of next_tabindex produce an error not in the changelog When one tried to migrate to 3.25, the error "class X initialization doesn't have a settabindex argument" can happen but the word "settabindex" is not present in the changelog which makes it hard to find to which modification this error is related.

Merge with branch 3.26

[py3.7,test] Use cubicweb-file >= 2.2.2 This includes changeset aa4a3a3d0c18 fixing import of os.errno.

[flake8] Fix errors in cubicweb/ext/test/unittest_rest.py

[test] Shorten prefix string in test_rql_role_with_unknown_vid With Python3.7, this test fails as the error message returned by rest_publish() is: <p>an error occurred while interpreting this rql directive: ObjectNotFound('toto')</p> while we previously assumed a comma after 'toto'. Fixing this by only shortening the prefix used in out.startswith().

[flake8] fix errors in cubicweb_i18ntestcube/views.py test file

[test] Pass __module__ upon instantiation of RegistrableInstance This gets rid of the deprecation warning from logilab.common.registry: DeprecationWarning: instantiate MyAFS with __module__=__name__ and solves a test error on Python 3.7.

Added tag 3.26.8 for changeset 91f75319a726

[pkg] Version 3.26.8

[doc] didn't had any questions

[doc] missing import, cw now require this explicitely

[doc] add actual link to previous post

[doc] missing import in code example