line tests to include min/max values

[huss]

Is your feature request related to a problem? Please describe.

PR #975 added error bars to the graphics. The line reading tests, many in src/server/test/web/readings.js, are simply ignoring the returned min/max. Tests need to be enhanced to also test min/max.

Describe the solution you'd like

The design document needs to be updated, the expected data needs to be updates, the spreadsheet to calculated expected values needs to be updated and the tests then need to check the new values. The expected value data should use the same format as the export of line data with min/max values.

Describe alternatives you've considered

We don't do automated testing. For now, that is where we are at but this should not continue too long.

Additional context

@huss can help with the expected values and spreadsheets if that is desired.