Merge branch 'sk2' into 'develop'

GUI/Model/Fit/FitParameterContainerItem.cpp

GUI/Model/Fit/FitParameterContainerItem.h

GUI/Model/Fit/FitParameterHelper.cpp

GUI/Model/Fit/FitParameterItem.cpp

GUI/Model/Fit/FitParameterItem.h

GUI/Model/Fit/FitParameterLinkItem.cpp

GUI/Model/Fit/FitParameterLinkItem.h

GUI/Model/Fit/FitParameterProxyModel.cpp

GUI/Model/Fit/FitSuiteItem.cpp

GUI/Model/From/GUIExamplesFactory.cpp

GUI/Model/Group/ItemCatalog.cpp

GUI/Model/Job/JobModelFunctions.cpp

GUI/View/Fit/FitObjectiveBuilder.cpp

GUI/View/Fit/FitParameterWidget.cpp

GUI/View/Fit/FitSessionController.cpp

GUI/View/PropertyEditor/ItemPropertyWidget.h

Tests/Unit/GUI/TestFitParameterModel.cpp