format moderation queue only at end, avoid O(N^3) bug

format moderation queue only at end, avoid O(N^3) bug

It was calling format hooks for each comment on the page.
When relativedate is enabled, that made it insert <script> tags
for each comment. And the browser loaded the same script over and over,
which was slow on its own. But that was nothing compared to running
the onload even over and over.. especially since the hook system
added a new call to the hook each time it loaded.

For a page with 10 comments, that caused the relativedate DOM parsing
code to run 1000 times, I think. Anyway, it was sloow. Now it runs once.