* Since 0.1

  - API CHANGE: `RingBuffer::new()` no longer takes an argument.
  - `Copy` trait is no longer required on most `RingBuffer` methods.
  - Added two methods for bulk copying data in/out of the ring buffer:
    `Reader::shift_into()` and `Writer::unshift_from()`.
  - Added 'Iterator` implementation to `Reader`.
  - Minor performance optimizations.