return value of condest(); related docu updates

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2983 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
chol(), Cholesky() {and some remnant rcond()...} updates, thanks to Roger Bivand`s questions

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/matrix@2984 edb9625f-4e0d-4859-8d74-9fd3b1da38cb