2018-08-03: changed snmp scan function
2018-08-13: code cleanup, add metrics
2020-06-08: changed snmp-scan function
2021-09-06: rewritten for CMK 2.0
2021-09-07: added WATO for check and discovery function
            renamed from checkpoint_vsx to checkpoint_vsx_system
2021-09-21: changed graph definition for packets graph to stack
2021-09-24: changed graph definition for connections graph to make it scale with 
            the active connections (suggested by raulcurro[at]gmail[dot]com)