* Do not spin if TCP connection blocks for writing (and add test case).
* Fail queries if TCP dies repeatedly, rather than retrying many times.
* Do not abort in a couple of places if TCP unexpectedly broken.
+ * Do not free something twice if query fails and is then cancelled.
Portability/compilation fixes:
* Move `extern "C" {' to after #include <...>'s.
* adnsresfilter default timeout changed to 1000ms.
* m1test script can invoke `hrecord' differently.
* regress/output-<case>.report file contains more useful info.
+ * TODO list and other docs updated slightly.
+ * Referrals with RD+RA set, or RCODE=Refused, don't generate warnings,
+ just debug messages. BIND does this kind of thing all the time.
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