rename SessioItem::parent() --> parentItem()

GUI/Model/BaseItem/ModelMapper.cpp

GUI/Model/BaseItem/SessionItem.cpp

GUI/Model/BaseItem/SessionItem.h

GUI/Model/Data/Data1DViewItem.cpp

GUI/Model/Data/DataPropertyContainer.cpp

GUI/Model/Model/FitParameterHelper.cpp

GUI/Model/Model/FitParameterModel.cpp

GUI/Model/Model/ModelPath.cpp

GUI/Model/Model/SessionModel.cpp

GUI/Model/Model/SessionXML.cpp

GUI/View/Fit/FitParameterWidget.cpp

GUI/View/Mask/MaskEditorActions.cpp

GUI/View/Plot2D/IntensityDataCanvas.cpp

GUI/View/PlotComparison/FitComparisonViewController.cpp

GUI/View/PlotComparison/PropertyRepeater.cpp

GUI/View/PlotSpecular/SpecularPlot.cpp

GUI/View/Projection/ProjectionsEditorCanvas.cpp

Tests/Unit/GUI/TestMapperForItem.cpp

Tests/Unit/GUI/TestSessionItem.cpp

Tests/Unit/GUI/TestSessionItemController.cpp