[datafeed] allow to use cwclientlib for datafeed's queries (closes #5456849)
HTTP based URLs will be handled by a CWProxy if:
- cwclientlib is available and
- the URL matches a cwclientlibrc config entry
Otherwise, fallback to previous implementation.
See https://www.cubicweb.org/project/cwclientlib
:Warning:
This comes with an API modification of DataFeedParser.retrieve_url: it used
to accept data and headers arguments to build GET or POST (if data was given)
queries, but this was not used by any known code and imply more complicated
code.
# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb. If not, see <http://www.gnu.org/licenses/>.