- no more "isLocked" - use getSource directly (locked is a confusing name)
- no more split parse/setValue functions. there's only one entry point each now, and all they do is pass along the source passed to it from its parser.
- no separate setters, use setValue(value, source)
- add a "game target" source, which is low priority and indicates to the user that the value would have been default but was changed to a better value for the game target