Auto merge of #43627 - Aaronepower:master, r=alexcrichton

Updated release notes for 1.20

[Rendered](https://github.com/Aaronepower/rust/blob/master/RELEASES.md)

RELEASES.md

+Version 1.20.0 (2017-08-31)
+===========================
+
+Language
+--------
+- [Associated constants in traits is now stabilised.][42809]
+- [A lot of macro bugs are now fixed.][42913]
+
+Compiler
+--------
+
+- [Struct fields are now properly coerced to the expected field type.][42807]
+- [Enabled wasm LLVM backend][42571] WASM can now be built with the
+  `wasm32-experimental-emscripten` target.
+- [Changed some of the error messages to be more helpful.][42033]
+- [Add support for RELRO(RELocation Read-Only) for platforms that support
+  it.][43170]
+- [rustc now reports the total number of errors on compilation failure][43015]
+  previously this was only the number of errors in the pass that failed.
+- [Expansion in rustc has been sped up 29x.][42533]
+- [added `msp430-none-elf` target.][43099]
+- [rustc will now suggest one-argument enum variant to fix type mismatch when
+  applicable][43178]
+- [Fixes backtraces on Redox][43228]
+- [rustc now identifies different versions of same crate when absolute paths of
+  different types match in an error message.][42826]
+
+Libraries
+---------
+
+
+- [Relaxed Debug constraints on `{HashMap,BTreeMap}::{Keys,Values}`.][42854]
+- [Impl `PartialEq`, `Eq`, `PartialOrd`, `Ord`, `Debug`, `Hash` for unsized
+  tuples.][43011]
+- [Impl `fmt::{Display, Debug}` for `Ref`, `RefMut`, `MutexGuard`,
+  `RwLockReadGuard`, `RwLockWriteGuard`][42822]
+- [Impl `Clone` for `DefaultHasher`.][42799]
+- [Impl `Sync` for `SyncSender`.][42397]
+- [Impl `FromStr` for `char`][42271]
+- [Fixed how `{f32, f64}::{is_sign_negative, is_sign_positive}` handles
+  NaN.][42431]
+- [allow messages in the `unimplemented!()` macro.][42155]
+  ie. `unimplemented!("Waiting for 1.21 to be stable")`
+- [`pub(restricted)` is now supported in the `thread_local!` macro.][43185]
+- [Upgrade to Unicode 10.0.0][42999]
+- [Reimplemented `{f32, f64}::{min, max}` in Rust instead of using CMath.][42430]
+- [Skip the main thread's manual stack guard on Linux][43072]
+- [Iterator::nth for `ops::{Range, RangeFrom}` is now done in O(1) time][43077]
+- [`#[repr(align(N))]` attribute max number is now 2^31 - 1.][43097] This was
+  previously 2^15.
+- [`{OsStr, Path}::Display` now avoids allocations where possible][42613]
+
+Stabilized APIs
+---------------
+
+- [`CStr::into_c_string`]
+- [`CString::as_c_str`]
+- [`CString::into_boxed_c_str`]
+- [`Chain::get_mut`]
+- [`Chain::get_ref`]
+- [`Chain::into_inner`]
+- [`Option::get_or_insert_with`]
+- [`Option::get_or_insert`]
+- [`OsStr::into_os_string`]
+- [`OsString::into_boxed_os_str`]
+- [`Take::get_mut`]
+- [`Take::get_ref`]
+- [`Utf8Error::error_len`]
+- [`char::EscapeDebug`]
+- [`char::escape_debug`]
+- [`compile_error!`]
+- [`f32::from_bits`]
+- [`f32::to_bits`]
+- [`f64::from_bits`]
+- [`f64::to_bits`]
+- [`mem::ManuallyDrop`]
+- [`slice::sort_unstable_by_key`]
+- [`slice::sort_unstable_by`]
+- [`slice::sort_unstable`]
+- [`ste::from_boxed_utf8_unchecked`]
+- [`str::as_bytes_mut`]
+- [`str::as_bytes_mut`]
+- [`str::from_utf8_mut`]
+- [`str::from_utf8_unchecked_mut`]
+- [`str::get_mut`]
+- [`str::get_unchecked_mut`]
+- [`str::get_unchecked`]
+- [`str::get`]
+- [`str::into_boxed_bytes`]
+
+
+Cargo
+-----
+- [Cargo API token location moved from `~/.cargo/config` to
+  `~/cargo/credentials`.][cargo/3978]
+- [Cargo will now build `main.rs` binaries that are in sub-directories of
+  `src/bin`.][cargo/4214] ie. Having `src/bin/server/main.rs` and
+  `src/bin/client/main.rs` generates `target/debug/server` and `target/debug/client`
+- [You can now specify version of a binary when installed through
+  `cargo install` using `--vers`.][cargo/4229]
+- [Added `--no-fail-fast` flag to cargo to run all benchmarks regardless of
+  failure.][cargo/4248]
+- [Changed the convention around which file is the crate root.][cargo/4259]
+- [The `include`/`exclude` property in `Cargo.toml` now accepts gitignore paths
+  instead of glob patterns][cargo/4270]. Glob patterns are now deprecated.
+
+Compatibility Notes
+-------------------
+
+- [Functions with `'static` in their return types will now not be as usable as
+  if they were using lifetime parameters instead.][42417]
+- [The reimplementation of `{f32, f64}::is_sign_{negative, positive}` now
+  takes the sign of NaN into account where previously didn't.][42430] 
+
+[42033]: https://github.com/rust-lang/rust/pull/42033
+[42155]: https://github.com/rust-lang/rust/pull/42155
+[42271]: https://github.com/rust-lang/rust/pull/42271
+[42397]: https://github.com/rust-lang/rust/pull/42397
+[42417]: https://github.com/rust-lang/rust/pull/42417
+[42430]: https://github.com/rust-lang/rust/pull/42430
+[42431]: https://github.com/rust-lang/rust/pull/42431
+[42533]: https://github.com/rust-lang/rust/pull/42533
+[42571]: https://github.com/rust-lang/rust/pull/42571
+[42613]: https://github.com/rust-lang/rust/pull/42613
+[42799]: https://github.com/rust-lang/rust/pull/42799
+[42807]: https://github.com/rust-lang/rust/pull/42807
+[42809]: https://github.com/rust-lang/rust/pull/42809
+[42822]: https://github.com/rust-lang/rust/pull/42822
+[42826]: https://github.com/rust-lang/rust/pull/42826
+[42854]: https://github.com/rust-lang/rust/pull/42854
+[42913]: https://github.com/rust-lang/rust/pull/42913
+[42999]: https://github.com/rust-lang/rust/pull/42999
+[43011]: https://github.com/rust-lang/rust/pull/43011
+[43015]: https://github.com/rust-lang/rust/pull/43015
+[43072]: https://github.com/rust-lang/rust/pull/43072
+[43077]: https://github.com/rust-lang/rust/pull/43077
+[43097]: https://github.com/rust-lang/rust/pull/43097
+[43099]: https://github.com/rust-lang/rust/pull/43099
+[43170]: https://github.com/rust-lang/rust/pull/43170
+[43178]: https://github.com/rust-lang/rust/pull/43178
+[43185]: https://github.com/rust-lang/rust/pull/43185
+[43228]: https://github.com/rust-lang/rust/pull/43228
+[cargo/3978]: https://github.com/rust-lang/cargo/pull/3978
+[cargo/4214]: https://github.com/rust-lang/cargo/pull/4214
+[cargo/4229]: https://github.com/rust-lang/cargo/pull/4229
+[cargo/4248]: https://github.com/rust-lang/cargo/pull/4248
+[cargo/4259]: https://github.com/rust-lang/cargo/pull/4259
+[cargo/4270]: https://github.com/rust-lang/cargo/pull/4270
+[`CStr::into_c_string`]: https://doc.rust-lang.org/std/ffi/struct.CStr.html#method.into_c_string
+[`CString::as_c_str`]: https://doc.rust-lang.org/std/ffi/struct.CString.html#method.as_c_str
+[`CString::into_boxed_c_str`]: https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
+[`Chain::get_mut`]: https://doc.rust-lang.org/std/io/struct.Chain.html#method.get_mut
+[`Chain::get_ref`]: https://doc.rust-lang.org/std/io/struct.Chain.html#method.get_ref
+[`Chain::into_inner`]: https://doc.rust-lang.org/std/io/struct.Chain.html#method.into_inner
+[`Option::get_or_insert_with`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.get_or_insert_with
+[`Option::get_or_insert`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.get_or_insert
+[`OsStr::into_os_string`]: https://doc.rust-lang.org/std/ffi/struct.OsStr.html#method.into_os_string
+[`OsString::into_boxed_os_str`]: https://doc.rust-lang.org/std/ffi/struct.OsString.html#method.into_boxed_os_str
+[`Take::get_mut`]: https://doc.rust-lang.org/std/io/struct.Take.html#method.get_mut
+[`Take::get_ref`]: https://doc.rust-lang.org/std/io/struct.Take.html#method.get_ref
+[`Utf8Error::error_len`]: https://doc.rust-lang.org/std/str/struct.Utf8Error.html#method.error_len
+[`char::EscapeDebug`]: https://doc.rust-lang.org/std/char/struct.EscapeDebug.html
+[`char::escape_debug`]: https://doc.rust-lang.org/std/primitive.char.html#method.escape_debug
+[`compile_error!`]: https://doc.rust-lang.org/std/macro.compile_error.html
+[`f32::from_bits`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_bits
+[`f32::to_bits`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_bits
+[`f64::from_bits`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_bits
+[`f64::to_bits`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_bits
+[`mem::ManuallyDrop`]: https://doc.rust-lang.org/std/mem/union.ManuallyDrop.html
+[`slice::sort_unstable_by_key`]: https://doc.rust-lang.org/std/primitive.slice.html#method.sort_unstable_by_key
+[`slice::sort_unstable_by`]: https://doc.rust-lang.org/std/primitive.slice.html#method.sort_unstable_by
+[`slice::sort_unstable`]: https://doc.rust-lang.org/std/primitive.slice.html#method.sort_unstable
+[`ste::from_boxed_utf8_unchecked`]: https://doc.rust-lang.org/std/str/fn.from_boxed_utf8_unchecked.html
+[`str::as_bytes_mut`]: https://doc.rust-lang.org/std/primitive.str.html#method.as_bytes_mut
+[`str::as_bytes_mut`]: https://doc.rust-lang.org/std/primitive.str.html#method.as_bytes_mut
+[`str::from_utf8_mut`]: https://doc.rust-lang.org/std/str/fn.from_utf8_mut.html
+[`str::from_utf8_unchecked_mut`]: https://doc.rust-lang.org/std/str/fn.from_utf8_unchecked_mut.html
+[`str::get_mut`]: https://doc.rust-lang.org/std/primitive.str.html#method.get_mut
+[`str::get_unchecked_mut`]: https://doc.rust-lang.org/std/primitive.str.html#method.get_unchecked_mut
+[`str::get_unchecked`]: https://doc.rust-lang.org/std/primitive.str.html#method.get_unchecked
+[`str::get`]: https://doc.rust-lang.org/std/primitive.str.html#method.get
+[`str::into_boxed_bytes`]: https://doc.rust-lang.org/std/primitive.str.html#method.into_boxed_bytes
+
+
 Version 1.19.0 (2017-07-20)
 ===========================
 
@@ -1679,7 +1863,7 @@ Tooling
 
 * [Test binaries now support a `--test-threads` argument to specify the number
   of threads used to run tests, and which acts the same as the
-  `RUST_TEST_THREADS` environment variable](https://github.com/rust-lang/rust/pull/35414)  
+  `RUST_TEST_THREADS` environment variable](https://github.com/rust-lang/rust/pull/35414)
 * [The test runner now emits a warning when tests run over 60 seconds](https://github.com/rust-lang/rust/pull/35405)
 * [rustdoc: Fix methods in search results](https://github.com/rust-lang/rust/pull/34752)
 * [`rust-lldb` warns about unsupported versions of LLDB](https://github.com/rust-lang/rust/pull/34646)