Fixed bug in tablog and tabcox. 

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/tab@6 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Tiny.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/tab@7 edb9625f-4e0d-4859-8d74-9fd3b1da38cb