API: Replace PATCH zone/rrset API with PATCH zone

PATCH zone updates multiple RRsets at once (and in one transaction).
regression-tests.api: allow extra args in create_zone()
API: merge domain manipulation from create and update

Remove code duplication.
API: correctly use lowercase compare for zone name
Add new SOA-EDIT-API SOA editing setting

This triggers whenever a record is changed through the API.
Merge pull request #1354 from zeha/api-consolidate-zone-update

API: Consolidate zone update plus SOA-EDIT-API