Progress on the overview, plus some work on support functions

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rgl/pkg/rgl@1167 79a1b648-8b68-254f-b20b-c0b50f5137bf
Progress...

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rgl/pkg/rgl@1168 79a1b648-8b68-254f-b20b-c0b50f5137bf
Cover everything now.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rgl/pkg/rgl@1169 79a1b648-8b68-254f-b20b-c0b50f5137bf