Apparently this was a mistake that has proliferated over a very long time. The Software item that was being modeled was actually the game/machine equivilent from SoftwareList. But because there's both an item called SoftwareList and a DAT type called SoftwareList, some wire got crossed and they were mentally combined. Undoing this allows for a more proper internal model, including a couple of extraneous keys that were included originally.
This change looks dramatic, but it's just separating out the already-split namespaces into separate top-level folders. In theory, every single one could be built into their own Nuget package. `SabreTools.Serialization` still builds the normal Nuget package that is used by all other projects and includes all namespaces.
