added option to output short running numbers

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/vegsoup@645 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
improved error message

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/vegsoup@646 edb9625f-4e0d-4859-8d74-9fd3b1da38cb