[RFC PATCH 5/5] cli: add support for deduplicating based on case insensitive address

[David Bremner]

Jani Nikula <jani at nikula.org> writes:

> Consider all variants of an email address as one, and print the most
> common variant.

Other than the quibbles already mentioned, the series looks ok to
me. For production it should have one or two tests I guess. Oh, and man
page updates. But you knew that I guess.

I can live with the current argument syntax, but since a certain a mount
of bikeshedding is expected, here is an alternative suggestion

--deduplication={none|mailbox|address}