* Test/TestWriteSimple.cxx: fix to gdcmHeader-gdcmHeaderHelper revamping.

* Test/TestWriteSimple.cxx: fix to gdcmHeader-gdcmHeaderHelper revamping.
      The default constructor invoked by the line
         gdcmHeader *f1 = new gdcmHeader( header );
      was gdcmHeader::gdcmHeader(bool) instead of the expected
      gdcmHeader::gdcmHeader(std::string const &, bool = false, bool, bool).
      Hence the parsing wasn't executed... See also below.
    * src/gdcmHeader.h: the declaration of gdcmHeader::gdcmHeader(bool)
      as explicit constructor didn't do the trick to fix the above problem.
      Could anyone explain why ?   --- Frog