Use Data Frames format

[alexanderzobnin]

The new Grafana Data Frame format is much more flexible and provides better UX when changing visualization types. So it makes sense to change old time series format to the data frame.

Work in progress:

• Convert each series to data frame
• Use wide format when it's possible (many series in one data frame)
• Add labels (host name and item name) to each field (time series)
• Align points in each series to prevent stacking graph issues
• Use item units configured in Zabbix if possible (percents, bits, Bytes, b/s, B/s, etc)
• Use value mappings from Zabbix (network interface statuse, host status, ect)

[isaqueprofeta]

I'm really looking forward to this. I've been wanting to help you with updating docs, but I think this change will be pretty big if implemented. Gonna wait for it.