it seems that both `Diff.treeToTree` and `Tree#diff` fail to return a `DiffList`, but instead return a `Diff` object. the documentation [states][1] that they should, so i'm wondering - is `DiffList` not supported anymore? was it replaced by another type? [1]: http://www.nodegit.org/api/tree/#diff [2]: https://github.com/nodegit/nodegit/blob/master/examples/diff-commits.js#L22