cppcheck fixes

BSplineSurfaceSelectionPlugin.cc

@@ -183,7 +183,7 @@ void BSplineSurfaceSelectionPlugin::updateSlotDescriptions() {
 
 //==============================================================================================
 
-void BSplineSurfaceSelectionPlugin::slotSelectionOperation(QString _operation) {
+void BSplineSurfaceSelectionPlugin::slotSelectionOperation(const QString& _operation) {
     
     SelectionInterface::PrimitiveType type = 0u;
     emit getActivePrimitiveType(type);

BSplineSurfaceSelectionPlugin.hh

@@ -135,7 +135,7 @@ private slots:
     void noguiSupported() {};
 
     // SelectionInterface
-    void slotSelectionOperation(QString _operation);
+    void slotSelectionOperation(const QString &_operation);
     void slotToggleSelection(QMouseEvent* _event, SelectionInterface::PrimitiveType _currentType, bool _deselect);
     void slotVolumeLassoSelection(QMouseEvent* _event, SelectionInterface::PrimitiveType _currentType, bool _deselect);