Save revamp

Switched to json-saves, which while slightly slower load (it feels like, atleast) is a *lot* more convenient on the dev side of things, since it's just mark things with [DataMember] and we're done. More editable saves as well (for better and worse). Same goes for definition files (but only for the better there). Been testing quite a bit, and everything seems to be working. Might still be old-system artifacts around.