Infrastructure

I think the descriptions of some of our types that have more than a single serialized representation are a bit confusing. Most of the types have only a single (XML) serialized representation, and the descriptions of those are very concise. But, for instance, Types.DateTime can also be passed in URLs, so it has an additional serialization type. And I think maybe we should try to structure the description of that to make it more clear. Maybe have two clearly separated sections for the two serialized representations and say what the contexts that each is used in (URL vs. XML in the HTTP body). Also, Types.DateTime mentions stuff about internal representations, which I think should be left out entirely, or included at the end in an "implementation tips" section.