Fixes

- Replacing RRSet owner directly in zone_add_rrset().
- Fixed check if owner in RRSets should be replaced in
  dnames_from_node_to_table().
- Fixed check for return value from dname_table_add_dname2()
  in dnames_from_rdata_to_table().

Zone compiler does not work well. Don't know if it is because of
my changes to the zone and node API.