refs #1289

refs #1289

Reverted back to blocking sockets, using NB sockets caused recv() returning too early in tcp_recv().

refs #1289

refs #1289

Todo: implement recv() timeout.

refs #1289

Todo: implement properly.

refs #1289

- If the last binary part was empty, the RDATA item was not created.
  This caused errors in transfer processing.

refs #1296 @1h30m

refs #1289

refs #1289

- Just a temporary hack for now - will send the partially
  assembled answer with a SERVFAIL error code.
- Should change it so that proper SERVFAIL response is sent.

refs #1300 @10m

- This must be handled as a NODATA case, not NXDOMAIN as in the
  case of NSEC.

fixes #1272 @5h

- However, it seems that nowhere it is required that the adjusting
  checks version. Maybe will be removed later. Now it was important
  to get that parameter to some lower-level functions which
  defaultly used version checking. This was causing problems when
  adjusting zone received by AXFR (nodes do not have the zone set).

- Was parsing one byte less then required.

Works:
* XFR/OUT

Broken:
* SOA query
* NOTIFY
* XFR/IN

refs #1289

- Other parts of the server expect new zone contents in the
  ns_xfr_t structure. Saving it there in ns_process_axfrin().

refs #1289

refs #983

- Keeping them in a separate linked list, passing it together with
  zone contents. Created new structure for holding both zone
  contents and the list of RRSIGs.
- Added debug output to zone contents.