- AXFR will use the tree traversing functions to get data from all
  nodes.
- Error in some node is carried on in the data passed to the
  function. Not sure if this works.

refs #755

- Added function ns_axfr() which finds zone to answer from.
- Added stub of ns_axfr_from_zone() which should do the actual
  AXFR answering.
- Using RCU when dereferencing pointer to zone db.

refs #755

refs #754

- Added a separate function to nameserver to parse query and get
  its type.
- Added special type for query types to dnslib/consts.h.

WARNING: The rest of the API is not modified yet to support the
         pre-parsed query, so you must still call
         ns_answer_request() with the unparsed query.

refs #750, 749

TODO: later remove the initialization of space for wireformat from
      dnslib_response_init(), so that it is not reallocated on a
      regular basis.

Server automatically translates relative config path to absolute.

- Macro for conditional compilation of hash table was not visible
  in dnslib. Moved to dnslib-common.h

- Counting of inserted zones.
- Errors in case the zone was not loaded or added.
- zones_load_zone() removed from API.

Conflicts:
	src/zcompile/tests/unittests_zp_main.c
	src/zcompile/tests/zcompile_tests.c

Removed synchronous zone loading, now fully async.

Commit refs #583.

refs #645

refs #645

Refs #725

Closes #725 @35m

Commit refs #583.

Changed parameter checks in dnslib_rrset_merge. Now calls dnslib_dname_compare instead of just comparing pointers.

- Added zones.c/h to Knot.files (again, there is some problem with
  the repo probably).
- Added some debug output.
- Removed zone database from server completely - allocation,
  initialization and destroying is done in the nameserver only.