title: HttpOpenRequest and Accept header
body: <p><code>HttpOpenRequest</code> takes an http accept header in a very weird format. Is it okay to ignore that parameter and add a normal accept header with <code>HttpAddRequestHeaders</code> later ?</p>
  
  <pre><code>  hfile = HttpOpenRequest(hLastConnection, 'GET', '/path',  NULL, NULL, NULL, INTERNET_FLAG_RELOAD | INTERNET_FLAG_KEEP_CONNECTION, 0);
    HttpAddRequestHeaders(hfile,'Accept: foobar', 14, HTTP_ADDREQ_FLAG_REPLACE or HTTP_ADDREQ_FLAG_ADD);
  </code></pre>
  
  <p>It does work (in WINE), but seems undocumented.</p>
  
  <p>Similarly, how is the situation for content-type and referer?</p>