* upstream/master: (342 commits)
  Update TODO list
  Fix some rustc warnings
  Fix some Clippy warnings
  Rustfmt
  Another fix for stderr support
  Rustfmt
  Simplify surrogate pair handling on windows
  Fix on windows when using stderr.
  Allow customization of the output stream
  Ignore all IO errors during completion
  Prepare 2.1.0 release
  Fix line refresh/redraw (#149)
  [unstable] Fix error: scoped lint `...` is experimental
  Update TODO list
  Flag ReadlineError, Cmd, KeyPress as non exhaustive
  Improve key press handling
  Fix clippy warnings
  Rename consts.rs to keys.rs
  Prepare 2.0.1 release
  Windows: fix enable_raw_mode
  ...

Change-Id: I4a5ea48918ba09f93037b8cabdb259af9edab1f2

Misc

Another fix for stderr support

 Simplify surrogate pair handling on windows

Fix on windows when using stderr.

This bug was introduced in #152

Allow customization of the output stream

Ignore all IO errors during completion

Misc

A full refresh must be performed when last hint is removed.

BackTab (Shift-Tab) on both unix and windows
F1...F5 on linux console
Ctrl-Space on windows

Prepare 2.0.1 release

Misc

(cherry picked from commit 17ae324d6d9ff7cc1f200eec73d8d9e831f8bb26)

(cherry picked from commit ecf4d1413f0a099bd8afe4bda5ea8dbd8b363f9f)

(cherry picked from commit 88b690ec718286c646822e4b89f28e667fbd4d54)

(cherry picked from commit 4d3da773f2e24625566ebe0a469fd31bbee38649)

Fix one clippy warning

Use into() instead of casting to c_ulong because of different types in some targets

Mark highlight_dynamic_prompt as deprecated

And fix example.