Add MustLogin exception and apply to communication module

common/framework/exceptions/mustlogin.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Rhymix\Framework\Exceptions;
+
+/**
+ * The "must login" exception class.
+ */
+class MustLogin extends \Rhymix\Framework\Exception
+{
+	public function __construct($message = '', $code = 0, $previous = null)
+	{
+		if ($message === '')
+		{
+			$message = lang('msg_not_logged');
+		}
+		parent::__construct($message, $code, $previous);
+	}
+}