directory layout cleanup !IMPORTANT

This patch changes the directory structure of dokuwiki as suggested
in http://www.freelists.org/archives/dokuwiki/06-2005/msg00045.html

As the changes.log is not managed through darcs you need to move it your
self to the new location in data/changes.log

I think I modified the code at all nessessary places, but I may have
forgotten a few things.

darcs-hash:20050605103842-9977f-af20f63c1d604888375d175d89ac6bd71566d47d.gz