Feature request: add command line option to kzonecheck to ignore RRSIG|NSEC|NSEC3 records

We use kzonecheck to check zone file after manual editing. But when dnssec is used, RRSIG and NSEC/NSEC3 records can't be veriried after edit because changes can cause records to be invalid.

To check result of manual edit it would help to add --ignore-dnssec command line option to ignore invalid RRSIG|NSEC|NSEC3 records.

Now we work around this issue by creating temp file from zone file and we filter out RRSIG and NSEC3 records out so we can test zone with kzonecheck before we load the zone.