improved infrastructure for parallel computing in mob()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@647 255f4249-2263-4417-b1ea-8498779e27a7
export predict.cforest as S3 method

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@648 255f4249-2263-4417-b1ea-8498779e27a7