fix global data issue

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/plot3d@89 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
alternative approach. The problem is, that this version now passes R-devel checks, but has then a note on R 3.1.1

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/plot3d@90 edb9625f-4e0d-4859-8d74-9fd3b1da38cb