Bug fix in plotting code of common.interval()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/dplr@842 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Removed the fixed bug from TODO

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/dplr@843 edb9625f-4e0d-4859-8d74-9fd3b1da38cb