Allow to pick the value from first, delta, diff,range

[oliverpool]

To match the latest state of grafana (grafana/grafana#7238)

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[portenez]

What are the chances of having this one released? Pie chart doesn't support delta which makes this plugin not that useful.

[alkalinecoffee]

Any update on this? Would also like to see it merged.

[oliverpool]

I just resolved the conflicts.
Are the maintainers (@daniellee / @briangann ?) willing to consider merging it?

[hoangnam2261]

Hi @oliverpool, when I used delta option, seem "end" parameter on api get data from datasources sooner 1 hours than the time on above time range box.
Have you checked this case?
I tried with singlestat panel, but it works fine.

[r2munz]

I have tried your commit without success. It would be indeed a great option to use other values in the pie chart