cleartext-indexing

[Daniel Kahn Gillmor]

This series is now rebased on top of Jani's unobjectionable 2-commit
"lib: signature content type indexing" series (as well as my third
commit on that thread), id:cover.1505329740.git.jani at nikula.org

I welcome review -- some flavor of this series has been kicking around
for over a year now, and it would be great to get more parts of it
merged.

Regards,

        --dkg