#3339 Make order of summary curves in plot predictable.

* The issue is sorting on pointer address for ensembles and summary cases. Instead sort by name.
* The crucial changes are in RiaSummaryCurveDefinition.cpp, RimSummaryCase and RimSummaryCaseCollection.
* The rest of the changes are just fallout from changing the pure virtual method RimSummaryCase::caseName to be const. The rest just follows.
* RimGridSummaryCase::caseName does alter something, but this variable was already declared mutable.

ApplicationCode/ProjectDataModel/Summary/RimSummaryCaseCollection.h

@@ -80,7 +80,7 @@ public:
     void                            loadDataAndUpdate();
 
     static bool                     validateEnsembleCases(const std::vector<RimSummaryCase*> cases);
-
+    bool                            operator<(const RimSummaryCaseCollection& rhs) const;
 private:
     caf::PdmFieldHandle*            userDescriptionField() override;
     QString                         nameAndItemCount() const;