rm 'explicit' from c'tor w/o args

GUI/Model/Beam/GrazingScanItem.h

GUI/Model/Beam/SourceItems.h

GUI/Model/Descriptor/AxisProperty.h

GUI/Model/Descriptor/SpanProperty.h

GUI/Model/Mask/MaskItems.h

GUI/Model/Mask/OverlayItem.h

GUI/Model/Tune/FitSuiteItem.h

GUI/Support/Data/SimulationOptionsItem.h

GUI/View/Canvas/ColorMapCanvas.h

GUI/View/Canvas/ProgressCanvas.h

GUI/View/Frame/StackedFrames.cpp

GUI/View/Frame/StackedFrames.h

GUI/View/Main/CentralWidget.h

GUI/View/Main/MainWindow.h

GUI/View/Plotter/ColorMap.h

GUI/View/Plotter/SpecularPlot.h

GUI/View/Tuning/ParameterTuningWidget.h