Implemented more suggestions by Keith:

- Made sure the 'Topic' title is only shown above the topics, not the icons.

- Automatically shorten the username when it is too long.  I implemented this
  as part of format_name() and could therefore nuke some code in the
  statistics module.  This is change is somewhat experimental and I'm willing
  to revert or change this if a number of people aren't too happy with this
  behavior.

- Left align the dates and authors: makes it easier/faster to scan.

- Made the little tablesort arrows clickable.