Log Message:
Changes 0.2:
* bugfix: SRV RR handling: fix domain name parsing and crash in case
  if no port is specified on input for SRV record query
* (trivial api) dns_set_opts() now returns number of unrecognized
  options instead of always returning 0
* dnsget: combine -f and -o options in dnsget (and stop documenting -f),
  and report unknown/invalid -o options (and error out)
* dnsget: pretty-print SSHFP RRs