Use pyramid flash queue for messages Use a 'cubicweb' flash queue and make sure it contains only one message so that the behavior is the same as cubicweb. Also, the 'message' property now returns both the cubicweb flash queue and the default flash queue. One big difference with the former behaviour is that messages set with set_message will survive a redirection, making set_redirect_message useless in most case. Closes #5298654

modname = 'pyramid_cubicweb'