except tcp-handler in the module internals

Conflicts:
	src/knot/dnssec/zone-events.c
	src/knot/updates/apply.c
	src/knot/zone/events.c
	src/knot/zone/zone-load.c
	src/knot/zone/zone.c

Switched to 'server' category from 'zone' category,
because the zone name from the configuration is not
available during module initialization.

- log_msg() logs into 'server' category
- log_msg_zone() and log_msg_zone_str() log into 'zone' category

Changeset refactor

See merge request !246

Conflicts:
	src/knot/updates/apply.c
	src/knot/updates/changesets.h

libknot dependencies cleanup

Divided files from `common` to `common` and `common-knot`, some moved to `libknot`.

Only those in `common` are used in `libknot` and only in .c files. `libknot` headers are no longer dependent on any headers outside `libknot`.

See issue #199

See merge request !245

Axfr denied log

See merge request !248