2016-04-03: rewrite the original cmk check
2016-05-24: added admin/operational state, fix for missing ap_name parameter
2016-07-01: added long output
2016-07-06: fixed: missing ap
2018-01-05: cosmetic changes, added metrics/cisco_wlc.py
2018-05-23: changed scan function, changed return values to yield
            code cleanup, removed unused oid's
2018-07-26: added code for incomplete ap data (missing lwap, data)
2018-08-03: changed cdp info: short interface name, dropped neighbor domain name, added S/N and Model to longoutput
2018-09-14: fixed issue with missing AP, fixed issue with SSH check
2021-07-16: rewrite for CMK 2.0
2021-07-17: added basic support for IOS-XE based WLAN controllers (C9800 family), without most of perfdata
            fixed _render_mac_address/_render_ip_address, code cleanup, removed WIPS check
            added lwap_uptime/time taken to join. changed perfdata to 1/s
2021-07-29: fix missing data from discovery (inv_ap_info)
2022-03-07: fixed handling of missing AP (THX to andreas[dot]doehler[at]gmail[dot]com)
2022-04-01: added RADIO MAC address
2022-05-31: removed "Software" from snmp detect function
2022-10-23: fixed warning in upgrade "non-empty params vanished" for vpn_entry
2023-02-21: added cluster function (backport from check_mk) THX to roger[dot]ellenberger[at]wagner[dot]ch
2023-02-21: moved gui files from ~/local/share/check_mk/... to ~/local/lib/check_mk... for CMK 2.1