This works by serializing and deserializing NPC AvatarAppearance to a notecard in the prim inventory and making the required baked textures permanent.
By using notecards, we avoid lots of awkward, technical and user-unfriendly issues concerning retaining asset references and creating a new asset type.
Notecards also allow different appearances to be swapped and manipulated easily.
This also allows stored NPC appearances to work transparently with OARs/IARs since the UUID scan will pick up and store the necessary references from the notecard text.
This works in my basic test but is not at all ready for user use or bug reporting yet.
