ada compliance
Filter <h1>, <h2>, and <h3> from allowed html in comments
The semantic structure of a discussion can be ruined if a comment includes code for headings that are at a higher level than the title of each comment. In discussions in Drupal, the title of the page is an <h1>, key regions are headed with <h2>s (which sometimes do not appear on screen but are available to screen readers to define regions that are obvious on visual inspection), and each comment begins with an h3. So if any heading is added within a comment, it should be no higher than an <h4>, right?
