added support for case weights in the summary function

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/caret@887 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
minor updates

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/caret@888 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added support for case weights in the summary function

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/caret@889 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added tests for case weights

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/caret@890 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added more info for case weights

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/caret@891 edb9625f-4e0d-4859-8d74-9fd3b1da38cb