message: chnaged label Unit->Chain in sequence widget
diff: @@ -242,7 +242,7 @@ export class SequenceView extends PluginUIComponent<{ }, SequenceViewState> {
  return {
  structure: PD.Select(structureOptions[0][0], structureOptions, { shortLabel: true }),
  entity: PD.Select(entityOptions[0][0], entityOptions, { shortLabel: true }),
  - unit: PD.Select(unitOptions[0][0], unitOptions, { shortLabel: true, twoColumns: true }),
  + unit: PD.Select(unitOptions[0][0], unitOptions, { shortLabel: true, twoColumns: true, label: 'Chain' }),
  operator: PD.Select(operatorOptions[0][0], operatorOptions, { shortLabel: true, twoColumns: true })
  }
  }
  