Implement option to replace existing alias when renaming an account; use database transactions when editing accounts

templates/account_delete.html.twig

@@ -18,7 +18,7 @@
     <p>You are about to delete the mail account "{{ accountUsername }}" including the following aliases:</p>
     <ul>
         {% for alias in aliases %}
-            <li>{{ alias['mail_address'] }}</li>
+            <li>{{ alias.getMailAddress() }}</li>
         {% endfor %}
     </ul>