dns/crypto-keys/opam

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

This one's mainly for Mort and Haris.  I'm working my way through all the 
libraries required to compile Signposts, and put stable versions up on OPAM.

I've taken all the forks of ocaml-dns and merged them (with the latest version 
using cstruct) into http://github.com/mirage/ocaml-dns.   Mort, there seem to 
be a lot of commented out conversion functions in the interfaces (packet.mli).  
Are these temporary or do you plan on putting them back at some point?

Haris, I've also adapted crypto-keys to 
http://github.com/mirage/ocaml-crypto-keys so it works with this DNS repo.  A 
query about licensing and tidy-up before release: it is currently GPL-2.0, 
which doesnt work for OCaml due to the static linking. Could you modify it to 
ISC and add your copyright to each file as with other code, so that it's 
suitable for release?

There are also generally a few build warnings, so it would be good to go 
through the code and make sure its suitable for release (e.g. there is a 
hardcoded IP address in the default DNSSEC lookup in ocaml-crypto-keys).

Good progress though; I should have the rest built very soon.

-anil