/// gdcm code used to be in gdcmCommon.h but due to a 'bug' in gcc/MacOSX
/// you cannot have static initialization in a multithreaded environment
/// since there is a lazy construction everything got skrew up somehow
/// Therefore the actual initialization is done in a cxx file (avoid
/// duplicated symbol), and an extern is used in gdcmCommon.h
/// gdcm code used to be in gdcmCommon.h but due to a 'bug' in gcc/MacOSX
/// you cannot have static initialization in a multithreaded environment
/// since there is a lazy construction everything got skrew up somehow
/// Therefore the actual initialization is done in a cxx file (avoid
/// duplicated symbol), and an extern is used in gdcmCommon.h