Add implicit function to clip block model with surface

[opengeostat]

Clipping a model (or a vtkImageData) will allows generating solid estimation domains from external or generated surfaces.

TODO:

• Create a function to clip model (vtkImageData) with surface (vtkpolydata), use this example: https://www.vtk.org/Wiki/VTK/Examples/Cxx/Meshes/ClipDataSetWithPolyData
• Create function to generate surface from points using linear rbf (already tested, add prototype in sandbox)
• Create function to generate implicit surfaces (intrusion style) interpolating distances. Will require adding function to generate contact points in drillholes and interior/exterior points