#134 CGOs don't ray trace two sided

[Thomas Holder]

None of the closed CGOs (cones, cylinders, spheres, ...) are ray traced from inside, even with two_sided_lighting=on.

python
from pymol import cmd, cgo
o = [ cgo.CONE,
           0.0, 0.0, 0.0,    # XYZ 1
           0.0, 0.0, 1.5,    # XYZ 2
           0.0,              # Radius 1        
           0.3,              # Radius 2
           1.0, 0.0, 0.0,    # RGB Color 1
           0.0, 0.0, 1.0,    # RGB Color 2
           0.0, 0.0,         # Caps 1 & 2
         ]
cmd.load_cgo(o, "test")
cmd.set("two_sided_lighting")
cmd.set_view((\
 0.885722756,   -0.094252989,    0.454539150,\
 0.136114433,    0.988856792,   -0.060191222,\
-0.443803966,    0.115182005,    0.888687670,\
 0.000002102,   -0.000001657,   -3.470972300,\
-0.120205641,    0.065616108,    0.809120178,\
 0.470814615,    6.470813751,  -20.000000000 ))
cmd.ray()
python end