use intl's native normalizer_normalize() in case the module is available
Merge pull request #10960 from owncloud/use-intl-module-master

use intl's native normalizer_normalize() in case the module is available
Fix the "addHeader($tag, $attributes, $text)" methods to not ignore the $text parameter

Also support closing tags with no text content given

Conflicts:
	lib/private/template.php
	lib/private/util.php
	lib/public/util.php
Deduplicate logic
Fix style

Fix style