gc3d bug

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rgl@1060 79a1b648-8b68-254f-b20b-c0b50f5137bf
clear3d and rgl.clear made aware of subscenes

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rgl@1061 79a1b648-8b68-254f-b20b-c0b50f5137bf
Fix text display in child subscenes

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rgl@1062 79a1b648-8b68-254f-b20b-c0b50f5137bf