Improve plot interfaces to be more flexible and convenient

As I understand it now, it it only possible to plot the exact data that is already present in memory

What one would often like to do: Plot something that is calculated from the raw data.

Possible implementation: Pass a lambda (or transform function) to all PlotXYZ() functions
The lambda transforms the data to our liking.
The lambda can be invocable on an arbitrary data type, but of course produces one result of a plottable type

I might post or push an example when I get it working
the CALL_INSTANTIATE_FOR_NUMERIC_TYPES thing seems to be getting in the way though.