Improve ordering of members when saved

[JimmyCushnie]

Currently the order members are listed in an apparently nondeterministic order, however in my experience it is almost always the derived class members and then the base class members, in the order the members are declared in the source file.

Order of saved members should be deterministic and reliable. The simplest way would be to do it alphabetically, but I would prefer to use the following rules. I am not sure if this is possible, but it's my ideal:

• Members are listed in order of least to most derived class
• Members within a single class are listed in the order of their listing in the source file

And perhaps we could have an attribute on members to customize their saving order.