prediction for experimental cforest

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@522 255f4249-2263-4417-b1ea-8498779e27a7
add FUN argument to predict_party.default and use it for predict_party.simpleparty

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@523 255f4249-2263-4417-b1ea-8498779e27a7
went through partykit vignette one more time, essentially ready

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@524 255f4249-2263-4417-b1ea-8498779e27a7
add quantile and density predictions for constparties

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@525 255f4249-2263-4417-b1ea-8498779e27a7
forest constructor

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@526 255f4249-2263-4417-b1ea-8498779e27a7