E4X xml-literal allowed xml-characters

Hi :)

js-beautify failed beautifying code with xml literals with entity-names og attribute-names containing: `-`, `.` or `_` (special characters, allowed in the xml-standard but missing in the xml-matching regexp in js-beautify (I overlooked them when I implemented it previously)).

The pull request has tests and fixes for both the JavaScript and Python implementation of js-beautify,

    Rasmus Erik :)