Add titles only option to unread listing

app/models/config.php

@@ -142,6 +142,7 @@ function get_sorting_directions()
 function get_display_mode()
 {
     return array(
+        'titles' => t('Titles'),
         'summaries' => t('Summaries'),
         'full' => t('Full contents')
     );

app/templates/item.php

@@ -88,7 +88,9 @@
     </ul>
     <?php if ($display_mode === 'full'): ?>
         <div class="preview-full-content" <?php echo Miniflux\Helper\is_rtl($item) ? 'dir="rtl"' : 'dir="ltr"' ?>><?php echo $item['content'] ?></div>
-    <?php else: ?>
+    <?php elseif ($display_mode === 'summaries'): ?>
         <p class="preview" <?php echo Miniflux\Helper\is_rtl($item) ? 'dir="rtl"' : 'dir="ltr"' ?>><?php echo Miniflux\Helper\escape(Miniflux\Helper\summary(strip_tags($item['content']), 50, 300)) ?></p>
+    <?php else: ?>
+        <p class="no-preview"></p>
     <?php endif ?>
 </article>