revive and finish resolver code

[hannesm]

this includes various enhancements:

• Ns now does not contain any glue (was brittle enough, and didn't lead to desired results)
• EDNS is now supported and used
• upgrade to TCP is done whenever a truncated packet is received
• retry now calls out to resolve again, rather than retransmitting the very same udp frame to the same remote
• storing resource records without a SOA is now possible (use case is to delegate to an open recursive resolve for a specific zone (such as .))
• fix DNSKEY encoding (blit with src and dst exchanged)

[hannesm]

SLOC    Directory       SLOC-by-Language (Sorted)
2541    src_top_dir     ml=2541
2436    test            ml=2436
1738    mirage          ml=1738
1374    server          ml=1374
1181    resolver        ml=1181
284     zonefile        ml=284
96      crypto          ml=96
30      pkg             ml=30

Totals grouped by language (dominant language first):
ml:            9680 (100.00%)

Total Physical Source Lines of Code (SLOC)                = 9,680
Development Effort Estimate, Person-Years (Person-Months) = 2.17 (26.02)
 (Basic COCOMO model, Person-Months = 2.4 * (KSLOC**1.05))
Schedule Estimate, Years (Months)                         = 0.72 (8.63)
 (Basic COCOMO model, Months = 2.5 * (person-months**0.38))
Estimated Average Number of Developers (Effort/Schedule)  = 3.02
Total Estimated Cost to Develop                           = $ 292,962
 (average salary = $56,286/year, overhead = 2.40).
SLOCCount, Copyright (C) 2001-2004 David A. Wheeler
SLOCCount is Open Source Software/Free Software, licensed under the GNU GPL.
SLOCCount comes with ABSOLUTELY NO WARRANTY, and you are welcome to
redistribute it under certain conditions as specified by the GNU GPL license;
see the documentation for details.
Please credit this data as "generated using David A. Wheeler's 'SLOCCount'."

but it doesn't tell me where to send the invoice :(