* Memory link hunt (by using valgrind --leak-check=yes PrintHeader).

        - added src/gdcmVR.cxx gdcmVR.h that objectify the previous
          gdcmHeader::_dicom_vr.
        - gdcmHeader::InitVRDict transfered as gdcmVR::gdcmVR().
        - gdcmHeader::dicom_vr is now of type gdcmVR* as opposed to
          VRHT*.
        - gdcmGlobal global object contained class added (see src/gdcmUtil.x)