- vtkClipDataSet already has an InsideOut option. Although
  it is unable to make precision cuts in the 2D plane,
  probably because it is scalar-based.
- This commit adds capability to invert output of
  vtkCookieCutter for all 2D, primary(including vtkPolygon),
  linear cells.
- A new class `vtkCellClassification` helps in the cutting
  procedure. It is provided externally to the CookieCut
  methods.
- Implements `vtkCell::CookieCut(..)` with similar
  signature as `vtkCell::Clip(..)` and `vtkCell::Contour(..)`
- The implementation is present in vtkVertex.cxx,
  vtkLine.cxx and vtkPolygon.cxx
- Composite cells are split up into constituent primary
  cells and each gets cut by clipper. (Just like contour)
- Implementation for vtkVertex is straightforward.
- For vtkLine, compute exterior strands just like the
  interior strands.
- For vtkPolygon, a vtkMutableUndirectedGraph instance
  is used to weed out exterior edges from a set of
  interior edges.
- Finally, resolve topo of each undirected graph, connect
  contiguous edges and output necessary polygons.
- In case the output looks like a non-manifold graph,
  the procedure is aborted.
- vtkQuad, vtkTriangle and vtkPixel shallow copy themselves
  into an instance of vtkPolygon which is then cut.
- Add tests for vtkCookieCutter::InsideOutOff()