* Test/ShowDicom.cxx : now can be used with an off-screen rendering to

   * Test/ShowDicom.cxx : now can be used with an off-screen rendering to
     avoid problems (otherwise, the difference test between the visible image
     and the reference is incorrect. If the reference is greater than the
     screen resolution, it's produce errors).
     Can be used for only one image. Can be used with a visible flag.
   * vtk/vtkGdcmReader.cxx : remove commented codes.
   * vtk/vtkGdcmReader.h : add the gdcmCommon.h include file to avoid warnings
     under windows at compilation
   * vtk/vtkgdcmViewer.cxx : reformat the file. Apply a default window/level
     for grayscale images
   * vtk/GdcmToBaseline.cxx : new program to easy create the reference image
   -- BeNours