[imp] pgp multipart/signed

[Chuck Hagenbuch]

Quoting Ilya <mail@krel.org>:

> I see that this RFC is pretty old, but I could not find anything that
> superceeds it. Would it be reasonable to add the protocol and micalg ?

Yup. See my commit message - I referenced the relevant RFC and asked for 
people to work on it. I made some progress, but we definitely need more.

-chuck

--
Charles Hagenbuch, <chuck@horde.org>
"A dream which helps you to live your reality with dignity
 and justice is a good dream." - Tariq Ramadan