* client/ClientPropertyManager.cpp, client/ClientPropertyManager.h:
A new class as a dummy property manager for the client side.
Never creates property objects.
* client/client.cpp: Instantiate the client property manager
during client initialisation.
* server/EntityFactory.cpp: Instatiate the server property manager
during server intialisation.
* common/PropertyManager.h: Add the singletons accessor, and
make the addProperty member return a pointer to the property.
* server/CorePropertyManager.h, server/CorePropertyManager.cpp:
Implement creating properties for server side entity objects.
* rulesets/Entity.cpp: Use the property manager singleton to
create properties if a new attribute is set which is not already
a property, and its also not already a soft attribute.
