2023-10-10: initial release
2023-10-16: added options  --keep-max  and --min-age 
2023-10-17: removed -p, -c, -d (use the long options instead: --path-in-inventory, --data-source, --inventory-columns)
            changed option --keep-max to --keep
            added option --check-user-data-only
            added SEED_DEVICES to user data, option -s/--sed-devices is now optional
            refactoring
2023-10-18: fixed --make-default not working
            added protected topologies
            changed get inventory data from file access to request via live status query
            get interfaces from autochecks changed to live status query
2023-10-19: cleanup removed "all" unused functions
            added option -u, --user-data-file to provide a user specific data file
2023-10-20: changed option -m/--make-default to -d/--default (-m is needed for -m/--merge
            added -m/--merge option
2023-10-27: improved matching of port name from CDP/LLDP data to interface (item) name of service
            improved internal data handling (HostCache)
2023-10-28: reworked handling of layers (see option -l/--layers)
            added option -l/-layers {CDP,CUSTOM,LLDP,STATIC} [{CDP,CUSTOM,LLDP,STATIC} ...]
            added section CUSTOM_LAYERS to user data file
            removed option -m/--merge, included in option -l/--layers
            removed option --lldp, included in option -l/--layers
            removed option --data-source, now handled in CUSTOM_LAYERS
            removed option --inventory-columns, now handled in CUSTOM_LAYERS
            removed option --path-in-inventory, now handled in CUSTOM_LAYERS
            removed lower limits for --keep and --min-age
2023-11-16: added option -b/--backend [LIVESTATUS, FILESYSTEM], 
            LIVESTATUS is the default for performance reasons -> for now only local site
            FILESYSTEM fethches the data directly form the inventory files -> use in distributed environments