Updated licence and title in line with CRAN maintainers's suggestions

git-svn-id: svn+ssh://r-forge.r-project.org/svnroot/retistruct@1355 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Merged with github

git-svn-id: svn+ssh://r-forge.r-project.org/svnroot/retistruct@1356 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Corrected and updated citation
Following CRAN upload, bumped version number and tweaked webpage and docs
Following CRAN upload, bumped version number and tweaked webpage and docs