updated default values of sizing parameters

	// (resp. a uniform) upper bound for the lengths of curve edges. This

	// parameter has to be set to a positive value when 1-dimensional features

	// protection is used.

	double edge_size = 1;

	double edge_size = 0;

	// facet_angle: a lower bound for the angles (in degrees) of the surface

	// mesh facets.

	double facet_angle = 25;

	// facet_size: a scalar field (resp. a constant) describing a space varying

	// (resp. a uniform) upper-bound or for the radii of the surface Delaunay

	// balls.

	double facet_size = 1;

	double facet_size = 0;

	// facet_distance: a scalar field (resp. a constant) describing a space

	// varying (resp. a uniform) upper bound for the distance between the facet

	// circumcenter and the center of its surface Delaunay ball.

	// cell_size: a scalar field (resp. a constant) describing a space varying

	// (resp. a uniform) upper-bound for the circumradii of the mesh

	// tetrahedra.

	double cell_size = 1;

	double cell_size = 0;

// optimizer options

// - https://doc.cgal.org/latest/Mesh_3/index.html#Mesh_3TheOptimizationParameters

				["--edge-size"]

				("A constant providing a uniform upper bound for the lengths of "

				 "curve edges. This parameter has to be set to a positive value when "

				 "1-dimensional features protection is used."

				 "--detect-features is used."

				 + fmt_default(edge_size));

		cli |= lyra::opt(facet_angle, "SCALAR")

				["--facet-angle"]