Unreleased

- Fixes stringify to only take ancestors into account when checking circularity.
  It previously assumed every visited object was circular which led to false positives.
  Uses the tiny serializer I wrote for Must.js a year and a half ago.
- Fixes calling the `replacer` function in the proper context (`thisArg`).
- Fixes calling the `cycleReplacer` function in the proper context (`thisArg`).
- Speeds serializing by a factor of Big-O(h-my-god-it-linearly-searched-every-object) it had ever seen. Searching only the ancestors for a circular references speeds up things considerably.