Remove unneeded XML-isms

<link> tags assume text/css if 'type' isn't specified:
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/style

<script> tags are assumed to be javascript if no 'type' is specified:
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script

Self-closing tags in html don't need the trailing slash.

The doctype says this is HTML, so we don't need to add XML attributes to
the <html> tag.
Merge pull request #4 from losingkeys/xmlisms

Remove unneeded XML-isms