Cleanup and more documentation.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/aqr@53 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Fixing package warning.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/aqr@54 edb9625f-4e0d-4859-8d74-9fd3b1da38cb