refs #5

* Test now detects invalid number of parameters.

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.