[ENH] <td|th class="heading"<a class="tableheading"> changed to <td|th class="heading"><a>, and <td|th class="heading">{self_link _class="tableheading" . . .} changed to <td|th class="heading">{self_link . . .}. (Coming up: updating CSS files accordingly, and sorting out <td class="heading"> vs. <th class="heading"> vs. <th>)