update DESCRIPTION

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/openair@835 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
remove code related to MannKendall

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/openair@836 edb9625f-4e0d-4859-8d74-9fd3b1da38cb