started the next big revision of psychotree
-> switch to partykit::mob as the core engine

R CMD build and INSTALL work fine, CHECK runs but with loads
of WARNINGs and NOTEs (but not ERRORs).



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/prefmod@224 edb9625f-4e0d-4859-8d74-9fd3b1da38cb