solved residuals problems

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bayesr@841 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
working on gamma distribution

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bayesr@842 edb9625f-4e0d-4859-8d74-9fd3b1da38cb