#431 Crash when generating DicomDir with several patient id containing leading whitespace

[Pierre Le Duff]

When we try to generate a dicom dir with several patient and one that has patient id like " 80073" it crashes.
In fact in Set method of gdcm::Attribute, values removes leading whitespace but when gdcm::Scanner does the mapping it keeps leading whitespace.
When we try to get filename from values it fails and we get an assert :

Scanner::TagToValue const & Scanner::GetMapping(const char *filename) const
{
  assert( filename && *filename );
}