In ordrer to avoid missbehaviour :

In ordrer to avoid missbehaviour :
gdcm::DocEntry is now specialized in
- gdcm::SeqEntry (Dicom Sequence) as opposed to :
- gdcm::ContentEntry (Dicom entry with a 'content')

gdcm::ValContent is now specialized in
 - gdcm::ValEntry (Dicom entry with a std::string representable value, i.e.
 characters value, or integers)
 - gdcm::BinEntry (Dicom entry with a non strig representable value

 (user hasn't any longer to thing about the precedence of his dynamic_casts)