change visibility icons

src/app/components/shared/comment-list/comment-list.component.html

@@ -62,12 +62,12 @@
 
       <button mat-icon-button (focus)="hideCommentsList=true" matTooltip="{{ 'comment-list.read' | translate }}"
               (click)="filterComments(read)">
-        <mat-icon [ngClass]="{read: 'read-icon'}[currentFilter]">visibility</mat-icon>
+        <mat-icon [ngClass]="{read: 'read-icon'}[currentFilter]">speaker_notes</mat-icon>
       </button>
 
       <button mat-icon-button (focus)="hideCommentsList=true" matTooltip="{{ 'comment-list.unread' | translate }}"
               (click)="filterComments(unread)">
-        <mat-icon [ngClass]="{unread: 'unread-icon'}[currentFilter]">visibility_off</mat-icon>
+        <mat-icon [ngClass]="{unread: 'unread-icon'}[currentFilter]">speaker_notes_off</mat-icon>
       </button>
 
       <button mat-icon-button (focus)="hideCommentsList=false" (click)="sortComments(currentSort); filterComments('')">

src/app/components/shared/comment/comment.component.html

@@ -23,7 +23,7 @@
       </button>
       <button mat-icon-button *ngIf="!isStudent || comment.read" [disabled]="isStudent" (click)="setRead(comment)">
         <mat-icon [ngClass]="{'read-icon': comment.read, 'not-marked' : !comment.read}"
-                  matTooltip="{{ 'comment-page.mark-read' | translate }}">visibility
+                  matTooltip="{{ 'comment-page.mark-read' | translate }}">speaker_notes
         </mat-icon>
       </button>
     </div>