New function to make power utility functions plots.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mpo@33 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Minor fix.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mpo@34 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Small edit.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mpo@35 edb9625f-4e0d-4859-8d74-9fd3b1da38cb