Modified Guinier issue on linearized plots

[butlerpd]

The rescale function of SasView provides for a generic rescaling of the x and y axis to be x^n,y^m and log or ln thereof.

However it also provides for named plots (which automatically set the x and y scales appropriately such as Kratky, Porod, Guinier etc. One of those is called Xs-Guinier. While the Gunier plot is very well known and the what is meant whenever a Guinier plot is requested, there are in fact two versions of what are often referred to as "modified Guinier" that apply to rods and discs respectivly.

• For rod, the plot y axis should be ln(I*Q) (instead of ln(I)), and the output is the rod radius. It should be applied in the Q^-1 range of the data. T
• For discs, the plot y axis should be ln(IQ^2) (instead of ln(I) or ln(IQ)), and the output is the radius of the disc. It should be applied in the Q^-2 region

Currently only the rod version is provided but is confusing as it is not stated which it is. If we are going to provide modified Guinier functions we should include both. Further they should be named so as to be obvious which is which
RodXS-Guinier and DiscXS-Guinier would probably work

NOTE: Identified during the NIST CNR summer school where the plot was incorrectly used for a disc cross-section but given this has existed since the earliest versions of SasView I find it hard to label as a 6.0.0 release requirement. Though relabeling the current xs-Gunier to RodXS-Guinier would be trivial and help avoid incorrect publications?