Add table pretty printing & alignment

Also dismissed implementing colgroups for now - had it but didn't like the
added complexity for a very questionable benefit - i've actually never used
that feature of org tables...

org/testdata/misc.html

@@ -20,10 +20,12 @@ crazy ain't it?
 <table>
 <tbody>
 <tr>
-<td><strong>foo</strong></td><td>foo</td>
+<td><strong>foo</strong></td>
+<td>foo</td>
 </tr>
 <tr>
-<td><strong>bar</strong></td><td>bar</td>
+<td><strong>bar</strong></td>
+<td>bar</td>
 </tr>
 </tbody>
 </table>