the output is now labelled as XHTML 1.0 Strict, since it does conform
to that DTD. also removed spurious cellpadding and cellspacing from
<div /> markup. also handle non-characters by conversion to
replacement character, and handle more control characters by
conversion to no-break space. finally, switch from &nbsp; to the
equivalent &#160; so that a non-validating XML parser (which is most
of them) can correctly parse this document.