add a bench_manual_deserialize benchmark
add a bench_manual_deserialize benchmark

infinityb/serde,Ticki/serde,3Hren/serde,csmulhern/serde,sidred10/serde,jmesmon/serde,tempbottle/serde,eefriedman/serde,Byron/serde,serde-rs/serde,oli-obk/rust-serde,Hoverbear/serde,JohnHeitmann/serde,thorbenk/serde,skade/serde,pcwalton/serde,erickt/serde