NOTE on how to use Append::MEsh with selected elements:
If we want to append only the selected faces of the mesh and call the Append::Mesh
with selected parameter = true, we must ensure that also the cofaces of inferior
order are selected (vertices and edges).
Otherwise what happen is that the vertices are NOT appended and then the appended
(selected) faces cannot be built.
On the other ahnd Append::Mesh will NOT change the selected flag of the input mesh, it must be done
before calling it. (check tri::UpdateSelection<CMeshO>::VertexFromFaceLoose(currentMesh->cm); )
The same problem for the adjacencies with higher order simplexes. In this cases they are simply not updated . For example, if only a few vertices are selected, and they have, say, VFAdj, it is ignored.
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