Next in Deadwood: Glued NS referrals

The next thing in Deadwood I will implement are glued NS referrals. Here is the general plan:

• If we get a NS referral upstream, make sure it is in bailiwick (actually, this bit of code has already been written).
• Store the NS referral in the cache.
• Then, make a new query to one of the NS servers, using the part of DNS space this NS record refers to as our new bailiwick.