Change Molecule::addAtomCopy() to use Atom::element()
Change Molecule::addAtomCopy() to use Atom::element()

This changes the Molecule::addAtomCopy() method to use
Atom::element() instead of Atom::atomicNumber() when adding
the new atom.

kylelutz/chemkit,kylelutz/chemkit,kylelutz/chemkit,kylelutz/chemkit