Add character set check when printing string value.
Add character set check when printing string value.

The stream operator for vtkDICOMValue was printing the raw contents of
string values without checking for the character set.  As a result, the
text was corrupted if a character set other than ascii or utf-8 was used.

dgobbi/vtk-dicom,dgobbi/vtk-dicom,dgobbi/vtk-dicom