Completely re-work colored output and tty handling.

This commit completely guts all of the color handling code and replaces
most of it with two new crates: wincolor and termcolor. wincolor
provides a simple API to coloring using the Windows console and
termcolor provides a platform independent coloring API tuned for
multithreaded command line programs. This required a lot more
flexibility than what the `term` crate provided, so it was dropped.
We instead switch to writing ANSI escape sequences directly and ignore
the TERMINFO database.

In addition to fixing several bugs, this commit also permits end users
to customize colors to a certain extent. For example, this command will
set the match color to magenta and the line number background to yellow:

    rg --colors 'match:fg:magenta' --colors 'line:bg:yellow' foo

For tty handling, we've adopted a hack from `git` to do tty detection in
MSYS/mintty terminals. As a result, ripgrep should get both color
detection and piping correct on Windows regardless of which terminal you
use.

Finally, switch to line buffering. Performance doesn't seem to be
impacted and it's an otherwise more user friendly option.

Fixes #37, Fixes #51, Fixes #94, Fixes #117, Fixes #182, Fixes #231

wincolor/README.md

@@ -0,0 +1,44 @@
+wincolor
+========
+A simple Windows specific API for controlling text color in a Windows console.
+The purpose of this crate is to expose the full inflexibility of the Windows
+console without any platform independent abstraction.
+
+[![Windows build status](https://ci.appveyor.com/api/projects/status/github/BurntSushi/ripgrep?svg=true)](https://ci.appveyor.com/project/BurntSushi/ripgrep)
+[![](https://img.shields.io/crates/v/wincolor.svg)](https://crates.io/crates/wincolor)
+
+Dual-licensed under MIT or the [UNLICENSE](http://unlicense.org).
+
+### Documentation
+
+[https://docs.rs/wincolor](https://docs.rs/wincolor)
+
+### Usage
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+wincolor = "0.1"
+```
+
+and this to your crate root:
+
+```rust
+extern crate wincolor;
+```
+
+### Example
+
+This is a simple example that shows how to write text with a foreground color
+of cyan and the intense attribute set:
+
+```rust
+use wincolor::{Console, Color, Intense};
+
+let mut con = Console::stdout().unwrap();
+con.fg(Intense::Yes, Color::Cyan).unwrap();
+println!("This text will be intense cyan.");
+con.reset().unwrap();
+println!("This text will be normal.");
+```