Release tokio v0.1.20, tokio-timer v0.2.21, and remove async-await-preview feature. (#1089)

The `async-await-preview` feature is removed as 0.1 will no longer track
Rust nightly.

This also bumps:
- tokio-timer (0.2.11).

tokio-timer/CHANGELOG.md

@@ -1,3 +1,8 @@
+# 0.2.11 (May 14, 2019)
+
+### Added
+- `Handle::timeout` API, replacing the deprecated `Handle::deadline` (#1074).
+
 # 0.2.10 (February 4, 2019)
 
 ### Fixed

tokio-timer/Cargo.toml

@@ -8,11 +8,11 @@ name = "tokio-timer"
 #   - README.md
 # - Update CHANGELOG.md.
 # - Create "v0.2.x" git tag.
-version = "0.2.10"
+version = "0.2.11"
 authors = ["Carl Lerche <[email protected]>"]
 license = "MIT"
 readme = "README.md"
-documentation = "https://docs.rs/tokio-timer/0.2.10/tokio_timer"
+documentation = "https://docs.rs/tokio-timer/0.2.11/tokio_timer"
 repository = "https://github.com/tokio-rs/tokio"
 homepage = "https://github.com/tokio-rs/tokio"
 description = """

tokio-timer/README.md

@@ -2,7 +2,7 @@
 
 Timer facilities for Tokio
 
-[Documentation](https://docs.rs/tokio-timer/0.2.10/tokio_timer/)
+[Documentation](https://docs.rs/tokio-timer/0.2.11/tokio_timer/)
 
 ## Overview
 

tokio-timer/src/lib.rs

@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://docs.rs/tokio-timer/0.2.10")]
+#![doc(html_root_url = "https://docs.rs/tokio-timer/0.2.11")]
 #![deny(missing_docs, warnings, missing_debug_implementations)]
 
 //! Utilities for tracking time.