[plt-scheme] GUIBuilder HOWTO/Tutorial website fixes

It looks like my GUIBuilder HOWTO/Tutorial is creating some
excitement.  I'm pretty happy.

It had many broken links for images.  I belive i have them all fixed now.

Thanks to Shriram Krishnamurthi and Mike Vidal for reporting this problem.

For those curious, I keep having these problems because i use mozilla
composer, which worked great when my site was 5 pages, but seems to be
a pain now, because i have to update every page manually.  I looked
into CSS but that just did layout, and i'd still have to splice the
border graphics/test in and out of the html files every time i changed
them.  My next stab is trying to move to texmacs
http://www.texmacs.org/ .  It seems like the *right* way to do it, but
looks like it'll be harder, as i think i'll be the first person (who
isn't working on the source code) to do so.

Anyway, my point is if people have ideas, for wysiwyg html editing &
scheme abstraction, i'd love to hear them.

Corey

(note, this is a new address that you *can* reach me at (i.e. i do
actually check this account regularly))