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

termcolor/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "termcolor"
+version = "0.1.0"  #:version
+authors = ["Andrew Gallant <jamslam@gmail.com>"]
+description = """
+A simple cross platform library for writing colored text to a terminal.
+"""
+documentation = "https://docs.rs/termcolor"
+homepage = "https://github.com/BurntSushi/ripgrep/tree/master/termcolor"
+repository = "https://github.com/BurntSushi/ripgrep/tree/master/termcolor"
+readme = "README.md"
+keywords = ["windows", "win", "color", "ansi", "console"]
+license = "Unlicense/MIT"
+
+[lib]
+name = "termcolor"
+bench = false
+
+[target.'cfg(windows)'.dependencies]
+wincolor = { version = "0.1.0", path = "../wincolor" }

termcolor/README.md

@@ -0,0 +1,88 @@
+termcolor
+=========
+A simple cross platform library for writing colored text to a terminal. This
+library writes colored text either using standard ANSI escape sequences or
+by interacting with the Windows console. Several convenient abstractions
+are provided for use in single-threaded or multi-threaded command line
+applications.
+
+[![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)
+
+[![Linux build status](https://api.travis-ci.org/BurntSushi/ripgrep.png)](https://travis-ci.org/BurntSushi/ripgrep)
+[![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/termcolor.svg)](https://crates.io/crates/termcolor)
+
+Dual-licensed under MIT or the [UNLICENSE](http://unlicense.org).
+
+### Documentation
+
+[https://docs.rs/termcolor](https://docs.rs/termcolor)
+
+### Usage
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+termcolor = "0.1"
+```
+
+and this to your crate root:
+
+```rust
+extern crate termcolor;
+```
+
+### Organization
+
+The `WriteColor` trait extends the `io::Write` trait with methods for setting
+colors or resetting them.
+
+`Stdout` and `StdoutLock` both satisfy `WriteColor` and are analogous to
+`std::io::Stdout` and `std::io::StdoutLock`.
+
+`Buffer` is an in memory buffer that supports colored text. In a parallel
+program, each thread might write to its own buffer. A buffer can be printed
+to stdout using a `BufferWriter`. The advantage of this design is that
+each thread can work in parallel on a buffer without having to synchronize
+access to global resources such as the Windows console. Moreover, this design
+also prevents interleaving of buffer output.
+
+`Ansi` and `NoColor` both satisfy `WriteColor` for arbitrary implementors of
+`io::Write`. These types are useful when you know exactly what you need. An
+analogous type for the Windows console is not provided since it cannot exist.
+
+### Example: using `Stdout`
+
+The `Stdout` type in this crate works similarly to `std::io::Stdout`, except
+it is augmented with methods for coloring by the `WriteColor` trait. For
+example, to write some green text:
+
+```rust
+use std::io::Write;
+use termcolor::{Color, ColorChoice, ColorSpec, Stdout, WriteColor};
+
+let mut stdout = Stdout::new(ColorChoice::Always);
+try!(stdout.set_color(ColorSpec::new().set_fg(Some(Color::Green))));
+try!(writeln!(&mut stdout, "green text!"));
+```
+
+### Example: using `BufferWriter`
+
+A `BufferWriter` can create buffers and write buffers to stdout. It does *not*
+implement `io::Write` or `WriteColor` itself. Instead, `Buffer` implements
+`io::Write` and `io::WriteColor`.
+
+This example shows how to print some green text to stdout.
+
+```rust
+use std::io::Write;
+use termcolor::{BufferWriter, Color, ColorChoice, ColorSpec, WriteColor};
+
+let mut bufwtr = BufferWriter::stdout(ColorChoice::Always);
+let mut buffer = bufwtr.buffer();
+try!(buffer.set_color(ColorSpec::new().set_fg(Some(Color::Green))));
+try!(writeln!(&mut buffer, "green text!"));
+try!(bufwtr.print(&buffer));
+```