PMP Delaunay remeshing - add manifold parameter as NP

[janetournois]

Issue Details

The PMP function PMP::surface_Delaunay_remeshing()
does not provide the manifold() option available in Mesh_3

It should be added.

[afabri]

Should that not be switched on under the hood, just because the input is a non-self-intersecting triangle mesh?