Make it possible to retrieve all properties in toDict
We used to retrieve only the properties that are specified in the
self.properties() dictionary, instead, we now iterate over the
key_fields and only use self.properties() if those are not specified.
Patch by: Sverre Rabbelier
"""Multi-consumer multi-producer dispatching mechanism
Originally based on pydispatch (BSD) http://pypi.python.org/pypi/PyDispatcher/2.0.1
See license.txt for original license.
Heavily modified for Django's purposes.
"""
from django.dispatch.dispatcher import Signal