add option for unweighted means in reorder.hclust

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2853 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
add scores.hclust (to be removed later)

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2854 edb9625f-4e0d-4859-8d74-9fd3b1da38cb