[wdoc] Remove fallback about xml.etree module Module xml.etree exists since python 2.5.

[wdoc] Avoid usage of deprecated xlm elementree getchildren() method Use list(node) as suggested by the deprecation warning.

[style] Make cubicweb/web/views/wdoc.py flake8-clean

[py3] Use six.text_type instead of unicode in wdoc views

[views/startup] drop a duplicate rql query in manage view Counting entities in `nb` is already done above this code, regression introduced by a85db6fa

Merge with 3.26

Added tag 3.26.4, debian/3.26.4-1 for changeset e1c1af68db86

[pkg] Version 3.26.4

[py3] ensure AjaxController return bytes publish() must return bytes, when the @ajaxfunc decorated method return None, this raised: TypeError: You cannot set Response.body to a text object (use Response.text)

[py3] Let InstanceCommand.run_arg() always return an int The caller of this method (which is method "run_args") does `max(status, self.run_arg(appid))` and run_arg might return None if the underlying <cmdname>_instance method returns None. On python3 max(1, None) breaks with "TypeError: unorderable types: int() > NoneType()". So we enforce run_arg() method to return an integer even if the underlying method returns None. This fixes call of "cubicweb-ctl i18ninstance" with Python3.