#4892 Add Comparison view drop-down to linked view master.

Works as shadow of the views comparison view setting.
Make it follow the dependent viewcontrollers managed view.
Comparison view dropdown moved to "Viewer" group in view panel.
Avoid infinite recursion loops when comparison views are set up in circle

ApplicationCode/ProjectDataModel/Rim3dView.h

@@ -166,6 +166,7 @@ public:
     bool       isMasterView() const;
     Rim3dView* activeComparisonView() const;
     bool       isScaleZEditable();
+    void       setComparisonView(Rim3dView* compView); 
 
     std::set<Rim3dView*> viewsUsingThisAsComparisonView();
 
@@ -310,6 +311,7 @@ private:
     QPointer<RiuViewer> m_overrideViewer;
     int                 m_comparisonViewOrgTimestep;
     double              m_comparisonViewOrgZScale;
+    bool                m_isCallingUpdateTimestepAndRedraw; // To avoid infinite recursion if comparison views are pointing to each other.
 
     caf::PdmField<QString>                 m_name_OBSOLETE;
     caf::PdmChildField<RimViewNameConfig*> m_nameConfig;
@@ -319,6 +321,5 @@ private:
     caf::PdmField<cvf::Color3f>            m_backgroundColor;
     caf::PdmField<bool>                    m_showGridBox;
     caf::PdmField<bool>                    m_showZScaleLabel;
-    caf::PdmField<bool>                    m_isComparisonViewEnabled;
     caf::PdmPtrField<Rim3dView*>           m_comparisonView;
 };