ENH: add more DCMTK applications

Applications added:

• dcm2xml: convert DICOM into XML representation
  (http://support.dcmtk.org/docs/dcm2xml.html)
• dsr2xml: convert SR DICOM into XML representation
  (http://support.dcmtk.org/docs/dsr2xml.html
• dsrdump: SR-specific version of dcmdump already included
  (http://support.dcmtk.org/docs/dsrdump.html)

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24197 3bd1e089-480b-0410-8dfb-8563597acbee