Magnet
Removes the need to have an undesired transformation in CbmMagnet.cxx Places magnet center 40cm upstream from the target as per the magnetic field placement. Magnet_v18a -> Magnet_v20a (with clamps used in setups with the RICH) Magnet_v18b -> Magnet_v20b (without clamps used in setups with the MUCH)