minor changes; ?? related ?? to hetero=TRUE ?

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/curves-etc@291 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
cosmetic; see also, ..

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/curves-etc@292 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
add lines() method

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/curves-etc@293 edb9625f-4e0d-4859-8d74-9fd3b1da38cb