Defect setup inequivalent single defect sites overwritten

Currently, asr.setup.defects correctly evaluates which single defect positions should be considered for the setup. However, due to the labeling of defects which is {defect_species}_{defect_position}, it might happen that for example two vacancies of same atomic species but different Wyckoff label do not get created both. What is needed is a unique label to account for this issue. I suggest something like {defectname}.{index}, for example v_O.0 for an oxygen vacancy at index 0 of the pristine supercell.