Page Cleanups and PLib

More cleanups to the page. No more evil <center> and <br> tags; they've been replaced by their standards-compliant counterparts. I also fixed small errors all over the site -- almost every page linked from the sidebar has minor updates, although most of them were HTML-related.

For those of you who are here to check out PLib, you might want to take a look at the CVS version. The CVS version has full autoconf/automake support, the networking API (including transparent SSL support), Richard Lowe's PCRE wrapper, and other nice stuff. A few warnings about the CVS version: the documentation is horribly out of date, and the networking API may still have some kinks that need to be ironed out. Anyway, have fun, and feel free to send me comments, criticism, patches, etc.