rijksoverheid-cookie-opt-in library does not respect html5 DOCTYPE

First of all i would like to thank Limoengroen for this great module.
We needed it to cope with this bureaucratic legislation.

Issue:
The rijksoverheid-cookie-opt-in library does not respect html5 doctype due to that it does more then it's designed to do.
Therefore it only works on xml:lang document headers

As stated in line 400 of libraries/rijksoverheid-cookie-opt-in/behaviour/cookies.js

      langCode = $("html").attr('xml:lang');
      this.langCode = langCode.toUpperCase();

This javascript is not escaped and therefore it breaks many other jquery / javascripts

Naturally the same flaw is in the minified version that the module uses.
Temporary fix is use a XML based header:
Copy the html.tpl.php from /sites/all/themes/omega/omega/templates/html.tpl.php to your_theme/templates/html.tpl.php
and change:

html lang="<?php print $language->language; ?>" dir="<?php print $language->dir; ?>"

into

html lang="<?php print $language->language; ?>" xml:lang="<?php print $language->language; ?>" dir="<?php print $language->dir; ?>"

related issues that can be closed when exceptions for this language redundancy for html5 doctype are included / filtered out:
Flexslider stops working and Cookie warning only display when overlay is active

Obviously this issue would be the same with HTML5 themes other then Omega.