ENH: Update OpenIGTLinkIF: Improve support for POINT and POLYDATA message

Fixes #3875 and #3907

$ git shortlog 2ffd26b..d56c985 --no-merges
Junichi Tokuda (10):
      ENH: Use MarkupsFiducial node for POINT messages
      STYLE: Rename vtkIGTLToMRMLPointMetaList to vtkIGTLToMRMLPoint
      STYLE: Rename vtkIGTLToMRMLPoint to vtkIGTLToMRMLPoints.
      ENH: Initial implementation of the PolyData converter.
      ENH: Export PolyData through OpenIGTLink. Attributes are not exported.
      ENH: Export attributes. All features for the POLYDATA converter are implemented.
      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.

From: Junichi Tokuda <tokuda@bwh.harvard.edu>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23827 3bd1e089-480b-0410-8dfb-8563597acbee