Remove documentation references to garbage collection

[steveklabnik]

Rust has never actually had a garbage collector, but we lied about it for years. Time to come clean. I'd like to give all the docs a once-over, and remove all references to garbage collection, except for Gc<T>, obviously.

For example, the lifetimes tutorial: http://static.rust-lang.org/doc/0.10/guide-lifetimes.html

[steveklabnik]

I would tag this 'E-Easy' and "docs" if I could tag things. :)

[alan-andrade]

I'm on this

[alan-andrade]

Ok, here is my final version.

#14387

[steveklabnik]

I think this is largely good to go. I'll be keeping a future eye out for it.

[geraldstanje]

i heard a presentation about rust talking about an optimal gc...is this on ice now? http://channel9.msdn.com/Events/Lang-NEXT/Lang-NEXT-2014/Panel-Systems-Programming-Languages-in-2014-and-Beyond

[steveklabnik]

There never was a GC, we just said there was. It was a reference count with cycle detection. The plan was to eventually turn it into a GC, but instead, it's just being removed.