* clean Cargo.toml and add parity codec support
* upgrade parity codec
* fix travis
* make clippy happy
* use zeroize instead of memsec
* fix zeroize and add test
* Update .travis.yml
* improve codec support
* fix
* add TODO for removing clear_fr
* Add a feature flag (that doesn't do anything yet).
* Give `clear_fr` a stronger type to prevent mistakes and ensure the
right amount of memory gets cleared.
* Re-export the engine and related types from `lib.rs`.
Weiliang Li