Added points which are on the boundary are added to the constrained segments

[Kevin-Mattheus-Moerman]

@DanielVandH I am working on a minimal example (only have a clunky one currently), but I've noticed that when one has added interior points that happen to be exactly on a boundary edges, they are then included/dded to the constrained segments provided. This seems to me to be undesirable behaviour. It would be better to exclude both "in" and "on" points from the triangulation.