Upgraded to Rust 0.6 syntax.

- removed pub from `pub impl A for B`
- replaced `const` with `static`
- implemented `Drop` and `Index` traits
- removed `pure` and `static` function keywords
- removed `DVec`
- added `self` parameters to methods
Specify types on `cast::transmute` calls.
Move attributes outside of test function.
Change `fail_unless!` to `assert!`.
Merge pull request #1 from metajack/rust-0.6-syntax

Changes for new Rust 0.6 syntax