much faster stacking with new mets::cluster.index. Examples updated

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/lava/pkg/lava@894 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
doc

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/lava/pkg/lava@895 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
method merge.glm
Merge branch 'master' of github.com:kkholst/lava