interface to modify the display range of the SetupPlot

[carandraug]

A comment from one of the publication reviewers is that it would be nice to adjust the range of the SetupPlot:

The display range of 300nm to 800nm is the standard range that the vast majority of users work within. As a future request it would be useful to be able to adjust this, for example it is rare for fluorophore emissions below 400nm to be imaged, so being able to personalise and select for example 400-700 would be a nicety, but not essential.