'of_trafo' now warns when supplied an unordered factor

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@844 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
'chisq_test' ignored 'xtrafo' and 'ytrafo'

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/coin@845 edb9625f-4e0d-4859-8d74-9fd3b1da38cb