Change io crate & add a small shell

library/std/.gitignore

@@ -2,6 +2,8 @@ Cargo.lock
 Cargo.toml
 build.rs
 target
+tests
+benches
 src/random.rs
 src/num
 src/prelude
@@ -18,7 +20,6 @@ src/tests_helpers.rs
 src/error.rs
 src/net
 src/rt.rs
-src/sys/args
 src/sys/args/mod.rs
 src/sys/args/unsupported.rs
 src/sys/thread_local
@@ -56,9 +57,7 @@ src/sys/sync/thread_parking/unsupported.rs
 src/sys/sync/once
 src/sys/sync/once/no_threads.rs
 src/sys/sync/once/mod.rs
-src/sys/fd
 src/sys/fd/mod.rs
-src/sys/process
 src/sys/process/mod.rs
 src/sys/process/env.rs
 src/sys/process/unsupported.rs
@@ -100,7 +99,6 @@ src/sys/helpers/mod.rs
 src/sys/helpers/wstr.rs
 src/sys/helpers/tests.rs
 src/sys/helpers/small_c_string.rs
-src/sys/fs
 src/sys/fs/mod.rs
 src/sys/fs/common.rs
 src/sys/fs/unsupported.rs
@@ -124,7 +122,6 @@ src/sys/os_str/bytes
 src/sys/os_str/bytes/tests.rs
 src/sys/os_str/bytes.rs
 src/macros.rs
-src/os
 src/os/mod.rs
 src/os/raw
 src/os/raw/mod.rs