Incompatible changes:
* RRs with mailboxes never rejected due to strange chars if _raw.
* Lack of a mailbox produces `.' not `<>'.
* Better usage messages (and no default query domain) for adnstest.
* Return EAGAIN from _check instead of EWOULDBLOCK.
Incompatible changes:
* RRs with mailboxes never rejected due to strange chars if _raw.
* Lack of a mailbox produces `.' not `<>'.
* Better usage messages (and no default query domain) for adnstest.
* Return EAGAIN from _check instead of EWOULDBLOCK.