title: mpdf not supporting chinese fonts
body: <p>I am using mpdf. When I try to write chinese words to the WriteHtml(), the resulting pdf containing square boxes instead of those fonts.</p>
  
  <pre><code>require 'mpdf/mpdf.php';
  $mpdf-&gt;allow_charset_conversion = false;
  $pdf = $this-&gt;pdf-&gt;load();
  $pdf-&gt;useAdobeCJK = true;
  $pdf-&gt;SetAutoFont(AUTOFONT_ALL);
  $mpdf = new \Mpdf\Mpdf(['mode' =&gt; 'utf-8']); 
  $mpdf-&gt;SetHeader('|&lt;h2&gt;Booking Invoice&lt;/h2&gt;|');
  $mpdf-&gt;setFooter('{PAGENO}'); 
  $mpdf-&gt;autoScriptToLang = true;
  $mpdf-&gt;autoLangToFont = true;    
  $mpdf-&gt;SetDisplayMode('fullpage');
   ob_start();
  
   include "test.php";
  $html = ob_get_contents();
  ob_end_clean();
  
  $mpdf-&gt;WriteHTML($html);
  </code></pre>
  
  <p>i tried mpdf 6.0 and above version, but still same result </p>
  
  <p>Please advice </p>
  
  <p>Thank you.</p>