Added (virtual) destructors to GMSH mesh density classes to avoid warnings.

FileIO/MeshIO/GMSHFixedMeshDensity.h

@@ -25,6 +25,7 @@ public:
 	GMSHFixedMeshDensity(double mesh_density);
 	void init(std::vector<GeoLib::Point const*> const& vec);
 	double getMeshDensityAtPoint(GeoLib::Point const*const) const;
+	virtual ~GMSHFixedMeshDensity() {};
 
 private:
 	double _mesh_density;

FileIO/MeshIO/GMSHMeshDensityStrategy.h

@@ -30,6 +30,7 @@ namespace FileIO
 class GMSHMeshDensityStrategy
 {
 public:
+	virtual ~GMSHMeshDensityStrategy() {};
 	virtual void init(std::vector<GeoLib::Point const*> const&) = 0;
 	virtual double getMeshDensityAtPoint(GeoLib::Point const*const) const = 0;
 };

FileIO/MeshIO/GMSHNoMeshDensity.h

@@ -22,6 +22,7 @@ namespace FileIO {
 class GMSHNoMeshDensity: public FileIO::GMSHMeshDensityStrategy {
 public:
 	GMSHNoMeshDensity() {};
+	virtual ~GMSHNoMeshDensity() {};
 	void init(std::vector<GeoLib::Point const*> const& vec)
 	{
 		// to avoid a warning here: