Ok, the commit that breaks everything! I have split pres2 up into pres2/
and presentations/ in CVS. I have put all the slides into a sub-dir of the
presentations/ directory the location of which you configure in config.php.
I have also changed it so that any image or example filename is relative to
the current slide's own directory. I have gone through and changed all the
existing presentations, but doublecheck to make sure I got them all please.