This re-orders text according to the Unicode bidirectional layout algorithm, using the [unicode-bidi](https://github.com/mbrubeck/unicode-bidi) crate. It uses the natural order of the text based on Unicode character properties and the CSS `direction` property. This does not yet support the CSS `unicode-bidi` property or the HTML `dir` attribute, but these should be straightforward to add. r? @pcwalton. Also depends on servo/unicode-bidi#4. Source-Repo: https://github.com/servo/servo Source-Revision: d3a36fafd948d7b9366feeca44f9ca9ad012d706