New ownership guide

This is the start of the new "Ownership" guide, to replace the lifetimes guide.

I'm still working on it, but I wanted to share my progress, as this guide is _very_ important, and I'd like as many eyes on it as possible. :smile: 
Hmmm. I've been saying 'resource' and trying quite hard to make it non-specific, even to memory, let alone heap memory.


> On Sep 10, 2014, at 15:57, John Hume <notifications@github.com> wrote:
> 
> In src/doc/guide-ownership.md:
> 
> > +One of Rust's most important features is its system of ownership. Other
> > +important concepts like borrowing and lifetimes follow from the ownership
> > +system too. A solid understanding of ownership is what separates an
> > +intermediate Rust programmer from a new one.
> > +
> > +At the same time, ownership is one of the more unique features that Rust has,
> > +and so it may seem a bit strange at first. With a little bit of studying, the
> > +ownership system will become second nature.
> > +
> > +# Ownership
> > +
> > +Virtually all programs make use of some kind of shared resource on your
> > +computer. The most common of these is memory. In order to use a particular
> > +resource, you are given a reference to that resource. It's through this
> > +reference that you are able to utilize the underlying resource. As an example,
> > +here is some Rust code which allocates some memory on the heap, and stores
> My concern is a reader mistakenly thinking these ownership concepts are unique to heap memory. It may be enough to say somewhere below that it applies to stack memory too.
> 
> \
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