Windows: fix testoptical.C (use only forward slashes in the path)
Windows: fix testoptical.C (use only forward slashes in the path)

karies/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,root-mirror/root,olifre/root,karies/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,olifre/root,olifre/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,olifre/root,karies/root,olifre/root,karies/root,root-mirror/root,karies/root,root-mirror/root,karies/root,karies/root,olifre/root,karies/root,karies/root,root-mirror/root