16 Upgrade notes for 2.2.8

Daemon changes

SNMP polling logic has been changed to always retry at least once. This should reduce the number of network errors, and might affect poller and network load.

Strict validation of SNMP responses has been turned off for single-variable SNMP requests. Items on misbehaving devices will now be monitored normally, but messages about such responses will be logged at DebugLevel=4.

If an IPMI device reports a threshold sensor and a discrete sensor under the same name, the threshold sensor is now preferred. This might fix strange readings (like "1" for fan RPM) or "not supported" errors.

Frontend changes

History related macros - {ITEM.VALUE}, {ITEM.LASTVALUE} and the {host:key.last()} functional macro - now obey the ZBX_HISTORY_PERIOD constant. This limits the amount of data the macro has to sift through and results in better performance.