Task: Fix PDF export

This fix helped by removing line breaks between tags:

$html = preg_replace('/>\s+</', '><', $html);

Also, I added this for debugging so I could view the generated HTML before it hits the PDF renderer, to see what is actually supposed to be outputted.

if($this->getProperty('debug_html')){
    header('Content-Type: text/html; charset=utf-8');
    echo $html;
    exit;
}