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 fetches the data directly form the inventory files -> use in distributed environments
2023-11-28: implemented MULTISITE as backend, via livestatus -> use in distributed environments, may become the default
2023-11-30: added RESTAPI backend --> this is kind of slow (20 seconds compared to 0.5 for MULTISITE)
2023-12-06: do not add devices from static connections to seed devices --> be more transparent
            added prefix option -> needs testing (THX to andreas doehler for the suggestion)
2023-12-21: adjusted for streamlined CDP/LLDP inventory format,
            needs at least CDP 0.7.1-20231221 and LLDP 0.9.2-2023122
            changed default backend from LIVESTATUS to MULTISITE
            added logger (option --log-level)
            removed option --debug
2023-12-22: added options --log-file and --log-to-stdout
2024-01-02: added new output format (option --new-format)
            fixed LOGGER.warn --> LOGGER.warning
            improved detection of missing hosts/interfaces
2024-01-03: fixed query in MULTISITE.exist
            added option --quiet
            renamed from create_topology_data to nvdct
2024-01-04: added SETTINGS section to nvdct.toml file -> defaults -> overridden by toml -> overridden by cli
                  only seed devices are additive (toml + cli)
            added L3v4 toml options: L3V4_IGNORE_HOSTS, L3V4_SUMMARIZE, L3V3_REPLACE
            moved from ~/local/bin/topology_data to ~/local/bin/nvdct