[PATCH 3 of 4] diff: accept "dict" as diff option

[Yuya Nishihara]

On Fri, 15 Jun 2018 10:48:34 +0200, Boris FELD wrote:
> > I'd rather force callers of ctx.diff() to build a diffopts object.
> Do you see a way to solves the import cycle?

Which one?

Maybe we can move patch.diff*opts() functions to either mdiff or new module
if that's the case.