Rust changes, derive and more

The `derive` attribute is used to derive some standard traits (e.g., `Copy`, `Show`) for your data structures. It was previously called `deriving`, and now it is `derive`. This is another minor change, but makes it more consistent with other attributes, and consistency is great!

Very helpful information for catching up with Rust 1.0.0-alpha changes.

There is no reason the compiler could not have mentioned this minor change.