(Taken from the 'ixfr' branch.)

- Adjusting zone contents after IXFR.
  - Loading NSEC3PARAM.
  - Checking if node is empty in the first walkthrough.
  - Putting dnames into the dname table.
  - Adjusting node and RRSets (as before).
- Checking CNAME and wildcard CNAME loops after IXFR.
- zone_contents_adjust_node() and
  zone_contents_dname_from_node_to_table() made public.
- Counting zone nodes in zone_conents_add_node() instead of
  during adjusting.
- Not setting node count in constructor.

refs #1550 @1h