Updated reference html files.
New reference files with `beautify_html` as False
- in self-closing tags ``/>`` is replaced with plain ``>``, and while
  generating a void-element it is always generated with ``/>``.
- If a tayra tag element that belongs to the class of void-elements,
  include a element-content it will be silently ignored, though a warning will
  be generated when compiling them.
- for teststd, beautify_html is disabled by default.