phonebook: only render tilde name if it differs from previous line

phonebook/index.html

@@ -45,12 +45,14 @@ title: phonebook
 			</tr>
 		</thead>
 		<tbody>
+			{% assign prevtilde = '' %}
 			{% for user in site.data.phonebook.community %}
 				<tr>
-					<td>{{ user.tilde }}</td>
+					<td>{% if prevtilde != user.tilde %}{{ user.tilde }}{% endif %}</td>
 					<td><code>{{ user.ext }}</code></td>
 					<td>{{ user.name }}</td>
 				</tr>
+				{% assign prevtilde = user.tilde %}
 			{% endfor %}
 		</tbody>
 	</table>