Fix POST handling. The issues where revealed by the unittests, which are ported from the cubicweb wsgi tests.

Use AuthTktAuthenticationPolicy

DB-saved session data Related to #4291173

Handle properly the '/https/*' urls CW uses a url prefix to detect https behing a reverse-proxy. A more proper way to do that is documented here in the waitress documentation (waitress is the default pyramid wsgi server): https://waitress.readthedocs.org/en/latest/#using-behind-a-reverse-proxy A later version should implement this, or use waitress in the 'pyramid' command. Related to #4291181

Correctly pass the multiple parameters to the cubicweb request When naively converted to a dict, the webob MultiDict will not set the multiple parameters (a same name with several values) in a way CW can understand. MultiDict.mixed() however, does exactly what CW needs: list values for keys with multiple values, and single value for the others. Related to #4291181

Add a wsgi application factory suitable for wsgi servers. This factory can generate a wsgi application for a cubicweb instance. It reads the instance name from the CW_INSTANCE environment variable, and activates the debugmode if CW_DEBUG is defined in environment. It is usable by uwsgi as the 'module' parameter : CW_INSTANCE=test uwsgi --plugins python,http --http 0.0.0.0:8080 --module pyramid_cubicweb:wsgi_application()

If any cube has a 'includeme' attribute, call config.include on it Related to #4291181

Add a make_cubicweb_application function This function will be used by the 'pyramid' cubicweb-ctl command. Related to #4291173

Fix session closing for cubicweb 3.19 Related to #4291173

Convert cubicweb.NotFound to HTTPNotFound Related to #4291173