Load all sample parameters - azimuth missing

[PreislerDalibor]

When I wanted to load an azimuth-resolved dataset (basically multiple histograms that originate from slicing of 2D pattern - integration and slicing was done outside of GSAS-II), the option to load the sample parameters was quite restricted. The Detector azimuth was not a selectable value. I made a custom change to GSASIIpwdGUI.py (in function OnAllSampleLoad I have manually added a value 'Azimuth' into a dict Names). Now it works and I suggest this to be incorporated into the GSAS-II as I see no reason for such restriction.