Threads and collections

Some more breakages and deprecations.

- spawn -> Thread::spawn
- some collections now live in collect-rs
- Regex is transitioning to crates.io
- some tasks can use bare functions instead of closures (cleaner code and no issues returning closures)
you're right, it does look strange. I think it came out of the "format" option on http://play.rust-lang.org/. I'll correct it...