* clients.conf: Convert all time intervals to new RFC 3339 syntax. * mandos: All client options for time intervals now take an RFC 3339 duration. (rfc3339_duration_to_delta): New function. (string_to_delta): Try rfc3339_duration_to_delta first. * mandos-clients.conf.xml (OPTIONS/timeout): Document new format. (EXAMPLE): Update to new interval format. (SEE ALSO): Reference RFC 3339.