v1.2.0 bump & changelog updates

Fix validation for dynamic records with IPv4+IPv6 subnets

Record RR handling improvements

Fix wrong re-use of sources for dynamic zones

The record got field names from the DNSKEY record by accident, fix this

Basically changing from
https://www.rfc-editor.org/rfc/rfc4034.html#section-2.1 to https://www.rfc-editor.org/rfc/rfc4034.html#section-5.1

So:
flags -> key_tag
protocol -> algorithm
algorithm -> digest_type
public_key -> digest

Include only existent yaml sources, fixes #1066

v1.1.1 version bump and changelog update

Fix typo when loading auto-arpa config

v1.1.0 version bump & changelog update

Resolved a typo that prevented the auto-arpa configuration options from
loading.

Meta processor

Spf deprecations

Add support for !include YAML directive

Preferable to have it run later after other processors have had their
change to add/remove records. Otherwise there may be PTRs created for
things that processors have filtered out. It's always possible to
manually include it in the appropriate places if you need finger grained
control.

Add a Processors list/section to the README