blocksample routine added

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1056 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
blocksample much faster id-variable generation + support for data.table

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1057 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
pmvn more robust-call

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1058 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
merged

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1059 edb9625f-4e0d-4859-8d74-9fd3b1da38cb