rustybuzz 0.1.0

An incremental harfbuzz port to Rust.
Documentation
# Change Log
All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](http://keepachangelog.com/)
and this project adheres to [Semantic Versioning](http://semver.org/).

## [Unreleased]

At this point, this is just a simple Rust bindings to a stripped down harfbuzz.

### Added
- An absolute minimum Rust API.
- harfbuzz's shaping test suite had been ported to Rust.

### Changed
- harfbuzz source code was reformatted using clang-format.

### Removed
- Subsetting. This is probably a bit controversial, but I want to port only the shaper for now.
  This is also removes around 7000 LOC.
- Arabic fallback shaper. Since it requires subsetting.
- Unused TrueType tables: BASE, COLR, CPAL, JSTF, MATH, STAT, bsln, fdsc, gasp, just, lcar, ltag, meta, name, opbd.
- All external dependencies: coretext, directwrite, freetype, gdi, glib, gobject, graphite, icu, uniscribe.
  Embedded harfbuzz relies only on internal TrueType implementation.
- Most of the non-shaping harfbuzz API.