Table headers are not handled properly

This happens when the oo generated (valid) html contains constructs like below:

<THEAD>
	<TR VALIGN=TOP>
		<TH WIDTH=14%>
			<P>Version</P>
		</TH>
		<TH WIDTH=14%>
			<P>Date</P>
		</TH>
		<TH WIDTH=72%>
			<P>Commentaire</P>
		</TH>
	</TR>
</THEAD>

Here the problem is the internal paragraph elements of 'th' elements. We can solve this problem in two ways:

1. Wrap the contents of 'th' element inside an embedded document --> results in enlarged table headings compared to original document.
2. Strip the isolated paragraph element from the 'th' element (move the contents up)

I'm going to implement the second approach because that preserves the original size of the table header. And this is the approach taken for table cell 'td' elements as well. Further, if the 'th' element contains more than one paragraph or more complex structures, it will be wrapped inside an embedded document (as done with td elements).