Added internal task links to activity stream

app/Template/event/task_internal_link_create_update.php

@@ -0,0 +1,16 @@
+<p class="activity-title">
+    <?= e('%s set a new internal link for the task %s',
+        $this->text->e($author),
+        $this->url->link(t('#%d', $task['id']), 'TaskViewController', 'show', array('task_id' => $task['id'], 'project_id' => $task['project_id']))
+    ) ?>
+    <span class="activity-date"><?= $this->dt->datetime($date_creation) ?></span>
+</p>
+<div class="activity-description">
+    <p class="activity-task-title">
+        <?= e(
+            'This task is now linked to the task %s with the relation "%s"',
+            $this->url->link(t('#%d', $task_link['opposite_task_id']), 'TaskViewController', 'show', array('task_id' => $task_link['opposite_task_id'])),
+            $this->text->e($task_link['label'])
+        ) ?>
+    </p>
+</div>