- The previous function tried to commit diff changes to zone (already
  there) and stored DNSSEC and diff changes unmerged.

Zone events IXFR-in

Honestly I have no idea if this will work for all the corner case that were mentioned in the old code. I think my next step will be to a make a test case for all of them.

Conflicts:
	src/knot/nameserver/axfr.c

contexts.

- Also removed knot_ from changesets

Conflicts:
	src/knot/nameserver/process_answer.c

- File xfr-in.c-> apply.c
- Removed obsolete API functions
- Doxygen and fuction reoraganization.

ref #209

ref #209

ref #209

This prevents problems when sharing/reusing the address bytes.

Zero-length msg_namelen prevents this.

 - Simpler DDNS signing, simpler changeset merging (todo: fix leaks)
 - Removed some needles helper functions and zone adjusting