typos

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2985 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
.set.factors(x, *) now also works when 'x' has no 'factors' slot

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2986 edb9625f-4e0d-4859-8d74-9fd3b1da38cb