Corrected and updated citation

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/retistruct@1357 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Following CRAN upload, bumped version number and tweaked webpage and docs

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/retistruct@1358 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Following CRAN upload, bumped version number and tweaked webpage and docs

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/retistruct@1359 edb9625f-4e0d-4859-8d74-9fd3b1da38cb