Guide Redux: Pointers

This is super, super WIP, but I'm going to go get lunch for a while, and figured I'd toss my work up here in case anyone wants to see my work as I do it.

This contains a new introductory section explaining the basics of pointers, and some pitfalls that Rust attempts to solve. I'd be interested in hearing how my explanation is, as well as if this belongs here. Pointers are such a crucial concept, I don't mind having a beginners' section on them in the main docs, even though our main audience is supposed to understand them already. Reasonable people may disagree, however.
Yeah, so I ran some C code to grab sample memory locations, and was also surprised that it grew upward, rather than down, but I _might_ have been using heap-allocated variables when I did it, which would make sense. Wonder why it was 32 bytes, though...

Anyway, I like that new wording, but in this case, the location of x would be the bottom of the stack, right?