Added test to demonstrate bug where AtomPlacer3D().numberOfUnplacedHeavyAtoms() counts explicit hydrogens as heavy atoms.

Signed-off-by: John May <john.wilkinsonmay@gmail.com>
Fixed bug where AtomPlacer3D().numberOfUnplacedHeavyAtoms() counts explicit hydrogens as heavy atoms.

Signed-off-by: John May <john.wilkinsonmay@gmail.com>