Names are shown instead of distances in MSA Editor

Scenario to reproduce:

1. Open "data/samples/CLUSTALW/COI.aln".
2. Open "Statistics" options panel tab.
3. Set any reference sequence.
4. Set "Show distances column" option.
   Expected state: the addition column is shown, it contains distances to the reference sequence.
   Current state: the addition column is shown, it contains sequence names.