ENH: Simplify vtkIGTLToMRMLPolyData::MRMLToIGTL() using vtkIGTLToMRMLPolyData::VTKToIGTLCellArray() function.
ENH: Simplify vtkIGTLToMRMLPolyData::MRMLToIGTL() using vtkIGTLToMRMLPolyData::VTKToIGTLAttribute() function.
ENH: Clean up the code.
STYLE: Remove debug code.