- References to old nodes replaced by references to new ones.
- Added API for this to node.
- Implemented reference fixing in XFR.

refs #1037 @20m

- Getting zone trees from zone contents.
- Applying functions to zone tree - zone tree functions require
  function working with zone tree node, i.e. the 'conversion'
  is done one layer above - in the zone contents.

refs #1037 @30m

closes #1040 @15m

- Copying node and copying RRSet separated to new functions.
- Removing empty RRSet from node.
- Various fixes of API usage.

refs #1034 @20m, #936 @2h

- node_new() sets flags to node.
- fixed node_set_previous() - properly connects the node to
  the chain of nodes.
- Modified calls to node_new() in all parts of the program.
- zone_contents_add_node() sets flags to created parents,
  checks if created nodes are not wildcard children,
  properly sets the last node's parent.
- Fixed zone_contents_add_nsec3_node() (parent setting).
- zone_contents_get_previous() + find/get_previous_nsec3() added.

- Adding new node during IXFR zone update implemented.

refs #1034 @2h

TODO: adding new node to the zone contents.

refs #936 @40m

refs #936 @3h

refs #1028

- Invalid reads and writes when checking references to already
  deleted nodes.
- Added macro for post-order reverse traversal to the AVL tree.
- Added function for post-order reverse traversal to zone-tree.
- References checking in node_free() are now done according to new
  parameter.
- Fixed usages of node_free()

refs #1028 @50m

- Added zone-contents module, most of zone functions moved there
  and adequately modified.
- Zone API functions just call the zone-contents functions now.
  Later should be removed totally.

- Few fixes.

refs #1028 @2h

- Freeing zone contents copy.
- Rolling back update.
- Cleaning up after update.

refs @936 @45m

refs #936 @15m

refs #936 @1h30m

- This will allow easy switching of the zone contents inside
  the zone structure, instead of switching the pointer to the
  zone somewhere in zonedb structures.
- Changed all uses of zone, removed some direct uses and replaced
  by uses of API.
- First parts of xfrin_apply_changesets().

refs #936 @1h30m

- Node deep copy copies the node structure, and creates a new
  copy of the skip list containing RRSets, but retains the
  references to owner domain name and all RRSets in the list.
- Added two new flags to node - old and new node.
- The new_node field should refer to a new copy of the node made
  during update.

refs #1002 @30m

- Checking if new node creation was successful.

refs #999 @5m

closes #999 @15m

refs #999 15m

refs #995 @5m

refs #999 @15m

refs #995 @5m

refs #995 @15m

refs #994 @5m

refs #994 @30m

refs #994 @10m

refs #994 @30m

- For now it is used besides the old tree and the contents are
  compared when used.

refs #994 @30m

refs #994 @20m

refs #994 @30m

- Added zone_get_apex().
- Fixed node_set_previous(), node_set_nsec3().

refs #995 @15m

- Added next node and nsec3 referrer pointers to node.
- Setting them in API functions for setting previous and nsec3
  nodes.
- Added API functions
  - dname_set_node()
  - node_get_owner()

TODO: In zone load and zone dump, node->prev and node->nsec3_node
      should be used only via API.

refs #995 @20m