Updated stylesheet

GUI/Application/ApplicationSettings.cpp

GUI/Application/ApplicationSettings.h

GUI/Support/IO/AbstractDataLoaderResultModel.cpp

GUI/View/Common/DocksController.cpp

GUI/View/Common/StyledToolbar.cpp

GUI/View/Common/StyledToolbar.h

GUI/View/Import/RealDataTreeModel.cpp

GUI/View/Instrument/InstrumentView.cpp

GUI/View/Instrument/InstrumentView.h

GUI/View/Instrument/InstrumentsTreeModel.cpp

GUI/View/Main/ActionManager.cpp

GUI/View/MaterialEditor/MaterialEditorDialog.cpp

GUI/View/SampleDesigner/SampleView.cpp

GUI/gui.qrc

GUI/images/caret-up.svg

GUI/images/checkbox-checked.svg

GUI/images/dock-close.svg

GUI/images/dock-float.svg

GUI/images/radio-checked.svg

GUI/styles/Base.stylesheet