I've added a few items to the refnet network plotting items, adding some colors and changing opacity.  More customization needs to be added to allow for titles, captions, etc. to be added to the ggplot2-generated graphics.

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