Use a wrapper around xml.etree.ElementTree.fromstring in python 2.x (…
Attributes aren't unicode objects, so they couldn't be directly used in info_dict fields (for example '--write-description' doesn't work with bytes).
E.g. do not match `property='og:video:type'` when `og:video` is requested.
Fixes #7108 HTML5 allows unquoted attribute values. See the "Unquoted attribute value syntax" section [1] for more information [1] http://www.w3.org/TR/html5/syntax.html
lang
Improve generic SMIL support
Closes #6406.