Log Message:
Update to 1.192

Upstream changes:
1.192     2013-09-07 21:00:55 America/New_York
          if Net::DNS is not available, do not test null mx validity

1.191     2013-09-04 21:52:50 America/New_York
          update bugtracker, repo, etc.

          mxcheck fails when remote MX record is "."

          drop use of bytes.pm; any bug fixed by that should be fixed again
          properly