some more references

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@549 255f4249-2263-4417-b1ea-8498779e27a7
added optional minbucket control argument -> mapped to minsize

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/partykit@550 255f4249-2263-4417-b1ea-8498779e27a7