Force for multi-surfaces
Made CNDO::GetForce, CNDO::CalcForce, ZindoS::CalcForce, and Mndo::CalcForce be able to treat multi-surfaces.
Completed with Rev. 270.
Made CNDO::GetForce, CNDO::CalcForce, ZindoS::CalcForce, and Mndo::CalcForce be able to treat multi-surfaces.