Packet processing cleanup.

src/knot/server/notify.c

src/knot/server/notify.h

src/knot/server/tcp-handler.c

src/knot/server/udp-handler.c

src/libknot/dname.h

src/libknot/dnssec/zone-nsec.c

src/libknot/nameserver/axfr.c

src/libknot/nameserver/axfr.h

src/libknot/nameserver/chaos.c

src/libknot/nameserver/internet.c

src/libknot/nameserver/internet.h

src/libknot/nameserver/ixfr.c

src/libknot/nameserver/ixfr.h

src/libknot/nameserver/name-server.c

src/libknot/nameserver/name-server.h

src/libknot/nameserver/ns_proc_query.c

src/libknot/nameserver/ns_proc_query.h

src/libknot/nameserver/update.c

tests/ns.c

tests/zonedb.c