Give a warning when negative/zero intensities are being plotted

[smk78]

Noted in #3793, point 13.

Is your feature request related to a problem? Please describe.
Because the default scales for plots are log-log, only positive non-zero intensities can be plotted. And SasView automatically adjusts the X-axis accordingly.

This can be very confusing, especially if the dataset being plotted predominantly contains intensities which are <=0 (as can happen in instances of poor baseline correction, etc).

Describe the solution you'd like
Could we provide a warning to the User somewhere that they may not be seeing all of the dataset and should check by Change Scale from log Y to Y?

[Cristian2299]

This was already discussed in #3762 and #3767. The PR #3778 added an error message in the log explorer. Can it work in your opinion?

[krzywon]

This was already discussed in #3762 and #3767. The PR #3778 added an error message in the log explorer. Can it work in your opinion?

This solution in #3778 is only triggered from the Set Graph Range widget which can only be triggered from the context menu of an existing plot. If data is sent to an existing or new log-log plot, and the data has values <= 0, no message is currently displayed.