Eurotherm: Display Calibration Graphs

As a scientist, I want the contents of my current Eurotherm calibration file to be displayed, so that I can see the shape of the curve and the limits of the table.
#### Acceptance Criteria
1. I can select a tab on the Eurotherm OPI to view the current calibration file as a graph.
2. The Calibration tab displays the currently selected Calibration file as a graph
3. The graph of the Calibration file should plot the data points listed in the file as squares (or circles or X's), so that individual data points can be distinguished from the line joining (or fitting) the points.
#### Notes
1. The calibration file is (usually) just a table of X-Y values.
1. There are (usually) no error bars
2. How should the points be joined up to draw a graph?
1. The points could be joined with straight-line segments.
2. Should a curve be fitted to the data-points? If so, how?
1. linear least-squares fitting?, some other curve (e.g. non-linear least squares)?
2. who determines which is the appropriate fitting algorithm?
3. Should the Calibration tab provide help with extrapolating the graph?
1. The answer to the question is "probably not". It seems like a dubious thing to do without good knowledge of the sensor, its characteristics and the calibration process? Which extrapolation techniques would be valid? How far can extrapolation be taken?
4. The decision to extrapolate (i.e. extend beyond the range of the data in the calibration file) should belong to the scientist.
3. Clearly, this feature could be added to any IOC/OPI pair that use calibration files.