This effectively doesn't do much for the time being since there's only one "Dat type" that's being used. Realistically, this is probably the best bet since a given DAT should not be restricted to an output type as much as an ItemType is bound to its data. This also removes the experimental classes that won't be in use for forever. More work still might need to be done but it is unknown at this point.
This massive change replaces the old "Rom" struct system with a new one that have different objects for each major item type. This required a lot of work and a lot of changes and has unfortunately been untested. But this is the first step in moving away from using structs. The next major step is converting Dat over to this as well.
