Calinski criterion for one class is now NA instead of Inf, -Inf or NaN

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2831 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
prc uses permute capabilities in anova example

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2833 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
less verbose use of treedive

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2834 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
update tests

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2835 edb9625f-4e0d-4859-8d74-9fd3b1da38cb