cleanup get_ref
cleanup .is_err and .is_ok. updated tcp.rs and ip.rs
cleanup .iter and .iter_err
 cleanup .unwrap and .unwrap_err fixing io tests and tcp.rs
cleanup .chain and .chain_err + fixing other files
cleanup .get and .get_err
cleanup .map and .map_err
to_either + fixes
auto merge of #7969 : MaikKlein/rust/master, r=erickt

I am doing some cleanups in std::result.