title: &nbsp causes a HTML5 validation fail
body: <p>I'm in the process of applying a "HTML4.5" approach to an existing XHTML1.0 Strict site. The idea is to change the doctype and apply semantic classes matching the new elements of HTML5 (&lt;<code>div class="aside"&gt;</code>, etc.) and do all that I can get away with, without Internet Explorer(IE) breaking (e.g. applying new <code>&lt;input&gt;</code> type attributes).</p>
  
  <p>The only problem I've encountered is that W3C's validator doesn't like <code>&amp;nbsp;</code> or <code>&amp;copy;</code>, while <a href="http://html5.validator.nu" rel="nofollow noreferrer">html5.validator.nu</a> has no problem.</p>
  
  <p>I know that HTML5 validators are experimental at this stage. Should I replace <code>&amp;nbsp;</code> with something? If so, what?</p>
  
  <p>My charset on this particular site is <code>UTF-8</code>.</p>