Move entity cache from web.request.ConnectionCubicWebRequestBase to repoapi.ClientConnection ResultSet._build_entity relies on an entity cache to avoid going round in circles (stack overflow due to infinite recursion) e.g. in a postcreate script. Clear the cache at commit/rollback time to avoid unexpected side effects; and explicitly clear the cache in a few tests where we mix ORM and RQL using the same connection.

# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s entity's classes"""