[patch] Doxygen tweaks

[Benjamin Kosnik]

>But with my patch:
>http://www.compsoc.man.ac.uk/~cow/tmp/html_user.patched/files.html
>
>And now there is a page for <algorithm>:
>http://www.compsoc.man.ac.uk/~cow/tmp/html_user.patched/algorithm.html

Yes, yes. Please check this in. I have doxygen markup too, and am waiting on you.

Can you do this consistently for all the std/ext/foo headers? If not
with this patch, the next will do. 

-benjamin