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.
include README
include COPYING
include COPYING.LESSER
include pylintrc
include jshintrc
include tox.ini
include flake8-ok-files.txt
include bin/cubicweb-*
include man/cubicweb-ctl.1
recursive-include extras *.bash_completion
include doc/*.rst
include doc/*.txt
include doc/Makefile
recursive-include doc/book *
recursive-include doc/tools *.py
recursive-include doc/tutorials *.rst *.py
recursive-include doc/api *.rst
recursive-include doc/_themes *
recursive-include doc/_static *
include doc/_templates/*.html
include doc/changes/*.rst
recursive-include doc/dev *.txt *.rst
recursive-include doc/images *.png *.svg
include doc/conf.py
include cubicweb/devtools/fix_po_encoding
recursive-include cubicweb/misc *.py *.png *.display
include cubicweb/web/views/*.pt
recursive-include cubicweb/web/data *.js *.css *.py *.png *.gif *.ico *.ttf *.svg *.woff *.eot
recursive-include cubicweb/web/wdoc *.rst *.png *.xml
recursive-include cubicweb/devtools/data *.js *.css *.sh
recursive-include cubicweb/i18n *.po
recursive-include cubicweb/schemas *.py *.sql
recursive-include requirements *.txt
recursive-include cubicweb/test *.py
recursive-include cubicweb/test/data bootstrap_cubes *.py *.sql
recursive-include cubicweb/test/data-rewrite bootstrap_cubes *.py
recursive-include cubicweb/test/data_schemareader *.py
recursive-include cubicweb/dataimport/test *.py
recursive-include cubicweb/dataimport/test/data *.py *.csv *.txt
recursive-include cubicweb/dataimport/test/data-massimport *.py
recursive-include cubicweb/devtools/test *.py
recursive-include cubicweb/devtools/test/data *.py *.txt *.js *.po.ref
recursive-include cubicweb/entities/test *.py
recursive-include cubicweb/entities/test/data *.py
recursive-include cubicweb/ext/test *.py
recursive-include cubicweb/ext/test/data *.py
recursive-include cubicweb/hooks/test *.py
recursive-include cubicweb/hooks/test/data-computed *.py
recursive-include cubicweb/hooks/test/data *.py
recursive-include cubicweb/sobjects/test *.py
recursive-include cubicweb/sobjects/test/data bootstrap_cubes *.py
recursive-include cubicweb/server/test *.py
recursive-include cubicweb/server/test/data bootstrap_cubes *.py source* *.conf.in *.ldif
recursive-include cubicweb/server/test/data-cwep002 *.py
recursive-include cubicweb/server/test/datacomputed *.py
recursive-include cubicweb/server/test/data-schema2sql toignore
recursive-include cubicweb/server/test/data-migractions bootstrap_cubes *.py
recursive-include cubicweb/server/test/data-schemaserial *.py
include cubicweb/web/test/testutils.js
recursive-include cubicweb/web/test *.py
include cubicweb/web/test/data/cubicweb_file/data/file.png
include cubicweb/web/test/data/cubicweb_file/wdoc/toc.xml
recursive-include cubicweb/web/test/data bootstrap_cubes pouet.css *.py
recursive-include cubicweb/web/test/data/static/jstests *.js *.html *.json
recursive-include cubicweb/wsgi/test *.py
include cubicweb/pyramid/development.ini.tmpl
include cubicweb/web/data/jquery-treeview/*.md
recursive-include cubicweb/skeleton *.py *.css *.js *.po compat *.tmpl rules
prune cubicweb/misc/cwfs