libripgrep: initial commit introducing libripgrep

libripgrep is not any one library, but rather, a collection of libraries
that roughly separate the following key distinct phases in a grep
implementation:

  1. Pattern matching (e.g., by a regex engine).
  2. Searching a file using a pattern matcher.
  3. Printing results.

Ultimately, both (1) and (3) are defined by de-coupled interfaces, of
which there may be multiple implementations. Namely, (1) is satisfied by
the `Matcher` trait in the `grep-matcher` crate and (3) is satisfied by
the `Sink` trait in the `grep2` crate. The searcher (2) ties everything
together and finds results using a matcher and reports those results
using a `Sink` implementation.

grep-regex/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "grep-regex"
+version = "0.0.1"  #:version
+authors = ["Andrew Gallant <jamslam@gmail.com>"]
+description = """
+Use Rust's regex library with the 'grep' crate.
+"""
+documentation = "https://docs.rs/grep-regex"
+homepage = "https://github.com/BurntSushi/ripgrep"
+repository = "https://github.com/BurntSushi/ripgrep"
+readme = "README.md"
+keywords = ["regex", "grep", "search", "pattern", "line"]
+license = "Unlicense/MIT"
+
+[dependencies]
+log = "0.4"
+grep-matcher = { version = "0.0.1", path = "../grep-matcher" }
+regex = "1"
+regex-syntax = "0.6"
+thread_local = "0.3.5"
+utf8-ranges = "1"