webgui6: better support TGraph painting
webgui6: better support TGraph painting

Same like with histogram, drawing of title and stat box should be
handled extra
root-mirror/root,root-mirror/root,karies/root,karies/root,olifre/root,olifre/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,karies/root,karies/root,karies/root,root-mirror/root,olifre/root,karies/root,olifre/root,olifre/root,root-mirror/root,karies/root,olifre/root,karies/root,karies/root,olifre/root,olifre/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,karies/root