Need to add support of positive values (which starts with plus sign) for the Items of the type "SNMP agent".

Need to add support of positive values (which starts with plus sign) for the Items of the type "SNMP agent" which have "type of information" equal to "Numeric (float)".
For example, in case zabbix_agent get negative value (with "" sign) from the SNMP device then such values are displayed in the Monitoring>Latest Data, but if zabbix_agent get positive value (with "+" sign) from the SNMP device then such items are not displayed at all in the Monitoring->Latest Data.