Add generic data export command (was: Add FOCUSTEM and FOCUSPOS plots)
Description of the feature
Recent versions of Kstars include FOCUSTEM
(ambient temperature when the image was taken) and FOCUSPOS
(position of the focuser) in the FITS headers.
It would be nice to render these in a plot so we can correlate FWHM with these parameters.
It can help us to establish the relationship between temperature delta and required focus position delta.
Now such analysis has to be done outside of Siril.