Base for model replacement

[Illeprih]

It still needs some extra touches as asset pooling(probably just a hashmap for the asset names, so stuff isn't read from disk multiple times) and the naming support (naming itself is easy, but will need some kind of mrg variant to pre-load everything on a partial unpack, so that the name refs are kept consistant), but it should still be worth reviewing before moving forward. Idea being that a modding event can be hooked up to the loading to have a mod be able to manipulate sobj assets. I've already added the script patches, so some of the flat textures might be off, but since I am referencing models' first animation instead of the ranom map one, it shouldn't have issues with invalid animations trying to play.