Missing covalent radius causes crazy bonds
Some elements have no covalent radius defined in the Blue Obelisk database, which causes too many bonds created by the vtkSimpleBondPerceiver. And with "too many" I mean bonds with everything:
Covalent radii should have reasonable default values, or vtkSimpleBondPerceiver should use reasonable default values when no data is available.
(see https://discourse.vtk.org/t/sensible-default-for-covalent-radius/2648)
