otherwise predicate on Bare_point cannot be called with Bare_point.
- Replace the typedef or Regular_triangulation_euclidean_traits :
typedef Weighted_point Point_2;
by a Weighted_point_mapper_2.
This will be necessary to adapt Kernel traits when Weighted_point
will be in Kernel
but this does not slove satisfactory the Weighted_point_2 - Point_2
type problem of regular, hence the need for the implicit converter.