Use innerHTML for likert row preset selection

Options are now possibly rich text. This needs to be taken care of.
Also use extra span tag to preserve all whitesoaces in the index-suffix.

#279

projects/editor/src/app/components/dialogs/likert-row-edit-dialog.component.ts

@@ -24,8 +24,8 @@ import { TextLabel } from 'common/models/elements/element';
         <mat-label>{{'preset' | translate }}</mat-label>
         <mat-select [(ngModel)]="newLikertRow.value">
           <mat-option [value]="null">{{'propertiesPanel.undefined' | translate }}</mat-option>
-          <mat-option *ngFor="let column of data.options; let i = index" [value]="i">
-            {{column.text}} (Index: {{i}})
+          <mat-option *ngFor="let column of data.options; let i = index" [value]="i"
+                      [innerHTML]="'<span>' + column.text + ' (Index: ' + i + ')</span>' | safeResourceHTML">
           </mat-option>
         </mat-select>
       </mat-form-field>