New Items for Instrument and co.

GUI/coregui/Models/BeamItem.cpp

GUI/coregui/Models/BeamItem.h

GUI/coregui/Models/DetectorItem.cpp

GUI/coregui/Models/DetectorItem.h

GUI/coregui/Models/InstrumentItem.cpp

GUI/coregui/Models/InstrumentItem.h

GUI/coregui/Models/ItemFactory.cpp

...Components/InstrumentWidgets/InstrumentSelectorWidget.cpp

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

GUI/coregui/Views/InstrumentView2.cpp

GUI/coregui/Views/InstrumentView2.h

GUI/coregui/coregui.qrc

GUI/coregui/images/config.png

GUI/coregui/mainwindow/mainwindow.cpp