cleanup get_ref
cleanup .iter and .iter_err
cleanup .unwrap and .unwrap_err fixing io tests
cleanup .chain and .chain_err + fixing other files
cleanup .get and .get_err
cleanup .map and .map_err
to_either + fixes
std: fix the casing of option::{Some,None} in the docs
std: Put the option tests into a tests submodule
core: correct the casing of result::{Ok,Err} in the docs
std and rustc: cleanup uses of result methods
std: cleanup imports in result::tests
auto merge of #8069 : erickt/rust/maikklein, r=erickt

Good evening,

This is a superset of @MaikKlein's #7969 commit, that I've fixed up to compile. I had a couple commits I wanted to do on top of @MaikKlein's work that I didn't want to bitrot.