Performance

- Added Timer class to display high resolution timing information.
- Found terrible bug in Table::optimize that was taking up 99.7%,
  on average, of the Table::rendering time, including sorting.  This
  fix naturally causes a 187-fold speedup of rendering.
- Changed report.cpp in handleCustomReport to only load pending tasks,
  instead of all pending tasks.  Subtle, but important difference.

html/task.html

@@ -121,6 +121,7 @@
                   <li>Performance enhanced by eliminating unnecessary sorting.
                   <li>Task now has a large (and growing) test suite and bug regression tests
                       to help ensure higher quality releases.
+                  <li>Fixed bug that caused performance hit during table rendering.
                 </ul>
 
                 <p>