#1 Include withs for associated classes

[Simon Wright]

It would be nice if class package bodies could 'with'
all other classes involved in associations (instead of
just the ones that the class holds referential
attributes for).

[Simon Wright]

It's not obvious why we 'with' classes for which we hold referential attributes in the first place! Still, the worst this change could do is to increase dependencies -- we won't cause anything new to be added to the domain's closure.