Natural Neighbor Coordinate Computation

Modules
	CGAL::natural_neighbor_coordinates_2()
	The functions natural_neighbor_coordinates_2() compute natural neighbor coordinates, also called Sibson's coordinates, for 2D points provided a two-dimensional triangulation and a query point in the convex hull of the vertices of the triangulation.
	CGAL::regular_neighbor_coordinates_2()
	The functions regular_neighbor_coordinates_2() compute natural neighbor coordinates, also called Sibson's coordinates, for weighted 2D points provided a two-dimensional regular triangulation and a (weighted) query point inside the convex hull of the vertices of the triangulation.