avoid using tools:::

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2600 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
MDSrotate handles non-orthogonal designs and prepares to receive more than one external vector

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2601 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
MDSrotate handles more than one external vector

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2602 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Document MDSrotate changes and version to 2.1-35

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/vegan/pkg/vegan@2603 edb9625f-4e0d-4859-8d74-9fd3b1da38cb