[hooks] major refactoring: * they are no "proper" appobject, selected when an event is fired according to its context * new module cubicweb.server.hook containing the Hook class and Operation class * deprecated SystemHook and PreCommitOperation classes * rewrite core server hooks as appobjects in the cubicweb/hooks directory -> deprecates hooksmanager, remove hooks, schemahooks, securityhooks cubicweb.server sub-modules -> new cubicweb.hooks sub-package -> get back to a (somewhat) working state

# Instructions here will be read before reading the schema
"""

:organization: Logilab
:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
# You could create your own groups here, like in :
#   add_entity('CWGroup', name=u'mygroup')