Add sorting by position in task list view

app/Template/task_list/sort_menu.php

@@ -16,6 +16,9 @@
         <li>
             <?= $paginator->order(t('Priority'), \Kanboard\Model\TaskModel::TABLE.'.priority') ?>
         </li>
+        <li>
+            <?= $paginator->order(t('Position'), \Kanboard\Model\TaskModel::TABLE.'.position') ?>
+        </li>
         <li>
             <?= $paginator->order(t('Title'), \Kanboard\Model\TaskModel::TABLE.'.title') ?>
         </li>

app/Template/task_list/task_icons.php

@@ -88,6 +88,8 @@
         </span>
     <?php endif ?>
 
+    <span title="<?= t('Position') ?>">(<?= $task['position'] ?>)</span>
+
     <?php if ($task['is_active'] == 1): ?>
         <div class="task-icon-age">
             <span title="<?= t('Task age in days')?>" class="task-icon-age-total"><?= $this->dt->age($task['date_creation']) ?></span>