Better output when singular values detected

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1230 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
start and end of interval added to output

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1231 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
rename

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1232 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
roxygen...

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1233 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
null-checks

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1234 edb9625f-4e0d-4859-8d74-9fd3b1da38cb