Factor out conversions, prepare for TLS
Factor out conversions, prepare for TLS

crossbeam-rs/crossbeam,huonw/crossbeam,crossbeam-rs/crossbeam,alexcrichton/crossbeam,Ticki/crossbeam,phil-opp/crossbeam,aturon/crossbeam,schets/crossbeam,msullivan/crossbeam,ticki/baguette,crossbeam-rs/crossbeam,crossbeam-rs/crossbeam,steveklabnik/crossbeam