Serialization for D part 2 of N

Well I did a quick hack and got a really basic version going. It only handles XML (with some ugly formatting restrictions) as the format and is restricted to structs, classes that are used like structs, and basic numeric types.

The up side is that the API/usage is just like I was expecting to do it and I didn't run into any problems. The down side is that I was kinda expecting it to take longer that this (all hyped up and nothing to do).

The next bit I'm going to work on, is to loosen up the XML formatting, but that should be easy. After that I'm going to dive into making polymorphism work.
On that note, I've thought of a few more issues I will need to deal with:

Public and Private Base Class Members

The off the cuff solution is to call base.Serialize either before or after dealing with all the direct members. But that doesn't address how to figure out what the base class members are.

Template Types.

The primary problem here will be making sure the correct type is deserialized, a.k.a. error checking. For internal nodes of struct types this shouldn't be a problems because there it is all static so if it's correct at the top level, it's correct throughout.

Template Types + Polymorphism

This adds another wrinkle to that problem. The wrinkle pops up where a template class derived from a non template class. This can result in trying to deserialize a type that wasn't instantiated in the code doing the deserialization.

Unions

This one is going to be nasty. I think I'll just ignore it for now. Later some sort of callback might make it work. As I said, not now.