Add option to limit the number of interpolated points

[DataBeaver]

I'd like to keep the interpolation option on so that missing one or two data points e.g. due to restarting collectd does not cause gaps in the graph. However some of my computers are not powered on all the time and I don't want interpolation over a longer downtime like being shut down for the night. Could you add a field to specify the maximum number of missing data points to interpolate over?