Maildir Refactor

[flatcap]

Hi Notmuch-lovers,

I've just created PR to refactor the Maildir/MH backend.
neomutt/neomutt#2689 in branch [devel/maildir]

It seems to work OK for me, using Maildir, but I'd some feedback from NotMuch users.

You don't need to do anything special, just check that it doesn't explode for your normal workflow.

Thanks ❤️