R CMD check warning on partial match of an argument

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/gravy@2351 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
export pick.model

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/gravy@2489 edb9625f-4e0d-4859-8d74-9fd3b1da38cb