Fix regression in test_langs.php

Commit 78cee358 added file Web.config to plugins and lang folder.
test_langs.php treated the file as a plugin folder and a language file.
Merge branch 'fix13-test_langs' of github.com:atrol/mantisbt into atrol-fix13-test_langs
Fix #17510: regression in test_langs.php
backport of 9e347c8b8ce5713e3804c880399a7ba3c4123fb4 to master

Add horizontal ruler before start of debug output

This helps seperate any debug output from the page generation within Mantis.