Protected Headers (2nd major revision, more testing!)

[David Bremner]

Daniel Kahn Gillmor <dkg at fifthhorseman.net> writes:

> Hi all--
>
> Way back in id:20180511055544.13676-1-dkg at fifthhorseman.net, i
> proposed support for protected headers (in particular, for being able
> to read and search for subject lines of encrypted messages which
> protect the Subject).  Although that series was reviewed by Bremner, i
> never managed to get it in shape for merging.
>
> This is a revision of that series, applied against the current master,
> having taken into account those reviews and the current state of the
> notmuch codebase.  I'm hoping that we can get it into 0.29 before the
> feature freeze.

It's in. I did bodge things up slightly due to the threading of patch
14, but I added the trivial patch with the one line change I missed.

d