add voximage represetation and test

src/Vtk/Math/vtkVoxImage.h

@@ -37,6 +37,7 @@
 #include "Vtk/uLibVtkInterface.h"
 
 class vtkImageData;
+class vtkActor;
 
 namespace uLib {
 namespace Vtk {
@@ -62,6 +63,7 @@ public:
   void ReadFromXMLFile(const char *fname);
 
   void setShadingPreset(int blendType = 2);
+  void SetRepresentation(Representation mode);
 
   void Update();
 
@@ -73,6 +75,7 @@ private:
   vtkVolume *m_Actor;
   vtkImageData *m_Image;
   vtkCubeSource *m_Outline;
+  vtkActor *m_OutlineActor;
 
   vtkXMLImageDataReader *m_Reader;
   vtkXMLImageDataWriter *m_Writer;