Add pattern syntax to indicate "do not publish a record for this IP"

[Kris Deugau]

I can't quite imagine a real situation you would really want to make sure an IP does not have rDNS, but it should be supportable. We need a pattern tag to indicate this case. It should iterate the same as any other template record, so that eg:

10.0.0.0/28 A+PTR %i.foobar.com
10.0.0.8/29 A+PTR <new tag>
10.0.0.12/30 A+PTR lil-%4.foobar.com

produces:

=10-0-0-0.foobar.com:10.0.0.0:ttl:::
=10-0-0-1.foobar.com:10.0.0.1:ttl:::
=10-0-0-2.foobar.com:10.0.0.2:ttl:::
=10-0-0-3.foobar.com:10.0.0.3:ttl:::
=10-0-0-4.foobar.com:10.0.0.4:ttl:::
=10-0-0-5.foobar.com:10.0.0.5:ttl:::
=10-0-0-6.foobar.com:10.0.0.6:ttl:::
=10-0-0-7.foobar.com:10.0.0.7:ttl:::
=lil-12.foobar.com:10.0.0.12:ttl:::
=lil-13.foobar.com:10.0.0.13:ttl:::
=lil-14.foobar.com:10.0.0.14:ttl:::
=lil-15.foobar.com:10.0.0.15:ttl:::

(blanking rDNS entries for .8 through .11)

[Kris Deugau]

Added in r463, note added to online template reference in r534. Effect cascades the same as other template patterns; the more-specific (smaller) netblock will always override the less-specific (larger) one, and a specific PTR or A+PTR will always override a template entry.