Implement save states of GUI in a config file (use QSetting)

src/Makefile.am

src/Makefile.in

src/plot/Plot1D.cpp

src/plot/Plot2D.cpp

src/plot/PlotToolBar.cpp

src/plot/PlotToolBar.h

src/plot/PlotWindow.cpp

src/plot/PlotWindow.h

src/plot/property/PropertyPlot2D.cpp

src/view/qt/QtColorMapWidget.cpp

src/view/qt/QtColorMapWidget.h

src/view/qt/QtPlotDataWidget.cpp

src/view/qt/QtStatusWidget.cpp

src/view/qt/QtStatusWidget.h

src/view/qt/QtToolBar.cpp

src/view/qt/QtToolBar.h

src/view/qt/QtWindow.cpp

src/view/qt/QtWindow.h