* vtk/vtkGdcmReader.[cxx/h]:

  * vtk/vtkGdcmReader.[cxx/h]:
        - UpdateProgress method should now be effective
        - removed the limitation on having only images loaded (as opposed
          to volumes),
        - when building a stack of images/volume, a lesser number of
          gdcmHeader and gdcmFile instances should be used (hopefully
          accelerating things).
        - when building a stack of images/volumes, files which are not
          loadable (wrong path-filename, wrong permissions on existing file,
          or file not parsable by gdcm) are replaced with a black image
          in the stack (for the caller to notice the problem).