Unnormalized 4th dimension is now dealt with.

Unnormalized 4th dimension is now dealt with.
User tells gdcm *where* it is.
File::SetFourthDimensionLocation(groupNb, elementNb);
After Load(), he may use int File::GetTSize();

As a proof of concept, PrintFile has one more option :
4Dloc=0x3001-0x1001, for instance.
One can see pixel size is now computed properly.

(VTK stuff is still missing)
--> Later!