ENH: parallelized walker init
ENH: parallelized walker init

bmockler/MOSFiT,villrv/MOSFiT,guillochon/MOSFiT,guillochon/MOSFiT,mnicholl/MOSFiT,guillochon/MOSFiT,mnicholl/MOSFiT,villrv/MOSFiT,mnicholl/MOSFiT,bmockler/MOSFiT,guillochon/FriendlyFit