Tests for server unit.
TAP protocol output.

- No epoll and master thread
- Workers are racing on recvfrom()
- Workers are natively blocked by recvfrom()
- Zero synchronisation overhead
- Presuming recfrom() is thread-safe

When processing DNAME, the actual qname should be used instead of
  the one from the query (e.g. when after CNAME).
Saving the actual qname before stripping and using it in DNAME and
  wildcard processing.

There are probably multiple bugs, needs a lot of testing and
  revision of the algorithm.
However, it should mirror the current state of the flowchart
  (230910-my).

If all labels matched & the node is empty non-terminal, continue
  the search.
If some labels matched & the node has no wildcard node, return
  NXDOMAIN.

Empty non-terminals are created after creating the zone list and
  before inserting into ZDS. The algorithm is quite straightforward
  - for each node it finds a 'parent' node and creates all nodes
    'missing' between the parent and the node. Search for parent
    optimized by saving the last parent + jumping directly to zone
    apex if number of common labes is equal to size of the zone
    apex' owner name.

Added function zn_is_empty().
Skipping empty nodes when processing non-authoritative nodes.

Changed answering algorithm so that DNAME is checked before
  wildcard and zone apex.
  (See query-processing-flowchart-200910-2.png.)
Implemented CNAME from DNAME synthesis - quite dumb, with a lot of
  copying (because of ldns).

Changed cute_start() to take more file names + passing these
  filenames from command line.

Was treating all nodes as delegation points.

Now answers 100% queries!

Documented TCP/UDP handlers and socket manager.
Cleanup of the socket manager APIs.

API consists of compulsory master thread routine and non-compulsory worker routine prototypes.

Conflicts:
	src/zone/zone-database.c

Zone nodes are inserted into zone data structure first, only
  marking delegation points and skipping their children.
All adjustments use zone data structure for lookup (speeds up
  delegation point adjusting significantly).
Showing progress of zone loading (list creation, zds filling,
  adjusting).