Update wordperfect and wpg filters to use new libs.

With this change, koffice requires libwpd-0.9, libwpg-0.2, and
libwps-0.2. These versions supposedly offer significant advantages over
the versions we were using before.

Most of the changes are simple CMake magic and replacing the code that
had been copied from wpg2odg with new versions from perfectspot (thanks,
Ariya Hidayat, for keeping these up-to-date!). However, a few changes
to the code were needed to integrate the new classes with koffice. In
particular, to get the wpg filter working, I had to re-enable (and
rewrite) the code for generating settings.xml and styles.xml.

I also had to fix the license information in some of the perfectspot
files to make Krazy happy -- they had the wrong FSF, Inc. address.

I have tested using an old wordperfect document I had lying around and
some wpg files I found on the web. All of these seemed to import
correctly. I also checked that Krazy was happy and that no new unit
tests failed.