Use private inheritance for Vector3D
Use private inheritance for Vector3D

A Vector3D is not an array, but use it as internal implementation.

lscalfi/chemfiles,Luthaf/Chemharp,lscalfi/chemfiles,Luthaf/Chemharp,chemfiles/chemfiles,chemfiles/chemfiles,Luthaf/Chemharp,chemfiles/chemfiles,chemfiles/chemfiles,lscalfi/chemfiles,lscalfi/chemfiles