New InstrumentModel class inheriting SampleModel.

GUI/coregui/Models/GUIExamplesFactory.cpp

GUI/coregui/Models/GUIExamplesFactory.h

GUI/coregui/Models/GUIObjectBuilder.cpp

GUI/coregui/Models/GUIObjectBuilder.h

GUI/coregui/Models/InstrumentModel.cpp

GUI/coregui/Models/InstrumentModel.h

...Components/InstrumentWidgets/InstrumentSelectorWidget.cpp

...s/Components/InstrumentWidgets/InstrumentSelectorWidget.h

...coregui/Views/Components/SampleDesigner/DesignerScene.cpp

GUI/coregui/Views/Components/SampleDesigner/DesignerScene.h

GUI/coregui/Views/Components/SampleDesigner/ILayerView.cpp

...oregui/Views/Components/SampleDesigner/SampleDesigner.cpp

GUI/coregui/Views/Components/SampleDesigner/SampleDesigner.h

GUI/coregui/Views/InstrumentView.cpp

GUI/coregui/Views/InstrumentView.h

GUI/coregui/Views/SampleView.cpp

GUI/coregui/Views/SampleView.h

GUI/coregui/mainwindow/mainwindow.cpp

GUI/coregui/mainwindow/mainwindow.h

GUI/coregui/mainwindow/projectdocument.cpp