GUI: Inconsistent image numbering
Image range in SubframeFindPeaks is 1 - n+1 but 0 - n in SubframeAutoIndexer. It's also 1 - n+1 in the DetectorWidget.
Image range in SubframeFindPeaks is 1 - n+1 but 0 - n in SubframeAutoIndexer. It's also 1 - n+1 in the DetectorWidget.