lighting


git-svn-id: https://geuz.org/svn/gmsh/trunk@20047 59c8cabf-10d6-4a28-b43f-3936b85956c4
put rtree in main code


git-svn-id: https://geuz.org/svn/gmsh/trunk@20048 59c8cabf-10d6-4a28-b43f-3936b85956c4