add option verify to enable graphing the number of successful responses.
if verify is enabled (default it is not) then a warning is emitted when
we do not get a response for all queries and critical if no query
succeeded.
add option timeout to be able to limit the time the plugin takes for
unresponsive servers. old max time was 75 seconds times 20 (25minutes).
new default max is 30 seconds timeout times 20 (10 minutes). with
setting a timeout of a few seconds this can now be reduced even more.
added warnings if average and or mean get close to the timeout.
