mcp-appstore

## 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][issue9]. Uses the tiny serializer I wrote for [Must.js][must] 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. [must]: https://github.com/moll/js-must [issue9]: https://github.com/isaacs/json-stringify-safe/issues/9