[etwist] upgrade post max size to 200Mo until it's configurable

[web session] fix web session id bug on automatic reconnection. The web session id should keep the first connection id, then differ of the repo connection id once some reconnection has been done (since the session cookie isn't updated in such cases). Also, use a lock to avoid potential race condition on reconnection.

[packaging] 3.8 depends on lgc 0.50 (new argument to dot generator in lgc.graph)

backport stable

[views] fix bug on gc debugging view

[testlib] ctrl_publish now allow to specify the controller id as argument

[web] stop having actions configurable through cwproperties: this clutter site management and .po files for a useless fonctionnality (which, where and how actions are displayed is handled by code)

[testlib] we should not replace db-name in sources, this cause undesired side effect (when running pytest on whole cw for instance). Proper fix in logilab.database

[web] put a fake object that raise Unauthorized on any attribute access as req.cnx and req._user, so we are properly asked to authenticated on any view that tries to do something with one of those attributes (instead of doing defensive programming everywhere we're doing that)

[etwist] we must call all error not handled in _render_request, else the thread fail silently and nothing ends up on the ui