Support for contour type

[iyerkrithika21]

Detecting if an input file is contour. Currently the number of points in the first cell of the polydata here and here are checked

Current version:

 // TODO This is temporary for detecting if contour until the contour type is fully supported
  if (reference_mesh->GetCell(0)->GetNumberOfPoints() == 2) {
    this->is_contour_ = true;
  }
}
}