Add Bezier cell types

Adds support for polynomial and rational bezier cell types. Anisotropic tensor product bezier quadrilateral and hexahedral cells are supported by appending the degree of each dimension to the end of the cell connectivity array.

The rational field is stored in a PointData field of a vtkUnstructured Grid. The cell degrees are stored in a CellData field of a vtkUnstructured Grid.

I was told to tag @dcthomp, @bob.obara, and @tjcorona.

This answer to the second most requested feature in Paraview, since rational Bezier cells are the base component of NURBS https://paraview.uservoice.com/forums/11350-general

6 new cell types are introduced:

• cell type 75: VTK_BEZIER_CURVE
• cell type 76: VTK_BEZIER_TRIANGLE
• cell type 77: VTK_BEZIER_QUADRILATERAL, supports anisotropic degree,
• cell type 78: VTK_BEZIER_TETRAHEDRON
• cell type 79: VTK_BEZIER_HEXAHEDRON, supports anisotropic degree,
• cell type 80: VTK_BEZIER_WEDGE, supports anisotropic degree.

See below some examples, more can be found here vtk_bezier_cells_v2.pdf