upgraded GSHHS files to 2.3.0

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/maptools@280 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
tidy

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/maptools@281 edb9625f-4e0d-4859-8d74-9fd3b1da38cb