2018-03-17: initial release
2018-05-29: added connection limit (fwConnTableLimit)
2018-05-31: changed form checkpoint_connections to checkpoint_fw_connections
            changed to checkpoint_fw_connections_default_levels to
            factory_settings['checkpoint_fw_connections_defaults']
2020-06-07: code cleanup
            added wato
            wadded warn/crit for connection rate
2020-06-08: changed snmp-scan function
            code cleanup
2021-08-23: rewritten for CMK2.0