allow containsResidue for ResidueView so an individual residue can be rendered.

Without this colouring a single residue didn't work with a residueView.

<code>
  var view = new mol.MolView(structure.full());
  var chainView = view.addChain(newResidue.chain(), false);
  var residueView = chainView.addResidue(newResidue, false);
  that.geom.colorBy(color.uniform('white'), residueView);
</code>