ipv6; bind

I've made some changes on the system; more are coming. Specifically so far:

• goat.gigo.com is now accessible on ipv6.


• irc.gigo.com is now accessible on ipv6.


• mail primary MX is on ipv6; secondaries will be soon.


• I changed from djbdns to bind. Lemme know if you see anything funky. If you edit zones here on gigo.com, I'll only install them if it passes a basic "will it load" test (using named-checkzone).


• ns3 and ns4.gigo.com are deprecated; they are currently aliased to ns1.gigo.com
• 
  
• I'm not publishing IPv6 NS records - waiting for word on whether I can get "glue" records published to .com for that.