Since there are loads of changes in 0.5 an upgrade will not work just "out of the box".
You need at least one template. If you want similar output as in version 0.3 use "simple_en".
It's now at the top of the file. Use the same $data_dir as in the old one, and don't forget the new $template_dir!
You need a new "config.txt" file in your data-dir.
If your groups.txt looks like this:
Guestbook|guestbook.txt Test|test.txt
then your config.txt should be:
BOARD | Guestbook | Guestbook | guestbook.txt BOARD | Test | Test | test.txt TMPL | default | simple_en | /pappalapapp/templates/simple_en/
Define a "default" template! Then you don't need to add a "template=" option
The old "groups.txt" is no longer used and can be deleted.
That's it!
The format of the data-files was not changed.
The script still accepts the "grp=" option to stay compatible, so you don't need to change links or ssi-calls