Zonemaster::LDNS::RR - common baseclass for all classes
    representing resource records.
    my $rr = Zonemaster::LDNS::RR->new('www.iis.se IN A 91.226.36.46');
This class overloads stringify and comparisons ('""',
    '<=>' and 'cmp').
  - new($string)
- Creates a new RR object of a suitable subclass, given a string
      representing an RR in common presentation format.
  - owner()
- Returns the owner name of the RR.
- name()
- An alias of owner().
- ttl()
- Returns the ttl of the RR.
- type()
- Return the type of the RR.
- class()
- Returns the class of the RR.
- string()
- Returns a string with the RR in presentation format.
- compare($other)
- Compares two Zonemaster::LDNS::RR. The TTL field is ignored, and the
      comparison of domain names is case insensitive.
    Returns an integer, where 0 indicates equality. 
- do_compare($other)
- Calls the XS "compare" method with the
      arguments it needs, rather than the ones overloading gives.
- to_string
- Calls the XS "string" method with the
      arguments it needs, rather than the ones overloading gives. Functionally
      identical to string() from the Perl level, except for being a tiny
      little bit slower.
- rd_count()
- The number of RDATA objects in this RR.
- rdf($postion)
- The raw data of the RDATA object in the given position. The first item is
      in position 0. If an attempt is made to fetch RDATA from a position that
      doesn't have any, an exception will be thrown.