new check.formula argument

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/eventhistory@200 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
prepare new CRAN version

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/eventhistory@201 edb9625f-4e0d-4859-8d74-9fd3b1da38cb