* src/gdcmUtil.cxx : compilation fix on Win32

   * src/gdcmUtil.cxx : compilation fix on Win32
   * src/gdcmUtil.[h|cxx] : Set the default GDCM UID in a static constant
     variable, to be easy found. Add methods to change the default UID.
     Amelioration of the CreateUniqueUID to use the correct default UID.
   * src/gdcmFile.cxx : correct use of the CreateUniqueUID method to create
     a new file
   -- BeNours