fixed self-shading issue in RFGraph
fixed self-shading issue in RFGraph

It seems that the T_EPSILON check during triangle intersection was not
enough to catch all self-shading cases. Subtracting T_EPSILON in the call
to RayPacket::hit() seems to have remedied the issue.

jeffamstutz/rfManta,jeffamstutz/rfManta,jeffamstutz/rfManta,jeffamstutz/rfManta,jeffamstutz/rfManta,jeffamstutz/rfManta