Conflicts:
	src/knot/zone/semantic-check.c

- function rrset_find_rr_pos()

- Small changes in other files, mostly reenabling disabled calls.
- new RRSet API function: delete all rrs from RRSet using other RRSet, but do not create RRSet that contains removed RDATA.

- fix in rrset.c
- rewritten rdata_remove function

- knot_rrset_rdata_reset() - sets RDATA section of RRSet to default values
- knot_rrset_copy_rr_from_rrset() - adds RR from given position and RRSet to input RRSet

- rrset_remove_rdata_pos, rrset_find_rr_pos

cov:968115

cov:970740, cov:970738

cov:970741

- Always setting previous node to NULL (it is done so when hash table is present, but [needs-review])
- Fixed error in rrset.c - missing &
- Added some old code to node.c, might be needed when server has no hash table.

refs #2137

- Other minor changes

refs #2137

Unify utils main functions.

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Currently without proper text output.

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It is possible to use service name too.

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- No XFR
- There was a reference to non-existent function in remote.c, removed, but needs a fix.

- No transfers, no updates, no zone loading.