"The Rust Programming Language," Take II

An updated version of https://github.com/rust-lang/rust/pull/19461

This version vendors aturon/rust-book@731f7bf and builds it when building the docs. This is almost great, except my `make`-foo is poor, so I have my own personal paths in `mk/docs.mk`. How should I best get around that?

/cc @brson 
So I'm not totally opposed, but @aturon wants to just make this the authoritative Rustbook, so I was thinking keeping it Cargo-build able would help WRT easier building. Maybe not.

> On Dec 18, 2014, at 21:22, Alex Crichton <notifications@github.com> wrote:
> 
> In src/rustbook/src/main.rs:
> 
> > @@ -0,0 +1,66 @@
> > +#![feature(slicing_syntax)]
> This repository has a bit of a different layout than Cargo ones, could the intermediate src folder be removed?
> 
> \
> Reply to this email directly or view it on GitHub.
>