Set libxml_use_internal_errors to allow parsing of invalid markup without E_WARNING

As suggested on [PHP.net:](http://www.php.net/manual/en/domdocument.loadhtml.php#95463) 
> DOMDocument is very good at dealing with imperfect markup, but it throws warnings all over the place when it does. 

> This isn't well documented here. The solution to this is to implement a separate aparatus for dealing with just these errors. 

> Set libxml_use_internal_errors(true) before calling loadHTML. This will prevent errors from bubbling up to your default error handler. And you can then get at them (if you desire) using other libxml error functions. 

> You can find more info here http://www.php.net/manual/en/ref.libxml.php