secp256k1 0.11.1

Rust bindings for Pieter Wuille's `libsecp256k1` library. Implements ECDSA for the SECG elliptic curve group secp256k1 and related utilities.

# 0.11.1 - 2018-08-22

* Put `PublicKey::combine` back because it is currently needed to implement Lightning BOLT 3

# 0.11.0 - 2018-08-22

* Update `rand` to 0.4 and `gcc` 0.3 to `cc` 1.0. (`rand` 0.5 exists but has a lot of breaking changes and no longer compiles with 1.14.0.)
* Remove `PublicKey::combine` from API since it cannot be used with anything else in the API
* Detect whether 64-bit compilation is possible, and do it if we can (big performance improvement)

# 0.10.0 - 2018-07-25

* A [complete API overhaul]https://github.com/rust-bitcoin/rust-secp256k1/pull/27 to move many runtime errors into compiletime errors
* Update [libsecp256k1 to `1e6f1f5ad5e7f1e3ef79313ec02023902bf8`]https://github.com/rust-bitcoin/rust-secp256k1/pull/32. Should be no visible changes.
* [Remove `PublicKey::new()` and `PublicKey::is_valid()`]https://github.com/rust-bitcoin/rust-secp256k1/pull/37 since `new` was unsafe and it should now be impossible to create invalid `PublicKey` objects through the API
* [Reintroduce serde support]https://github.com/rust-bitcoin/rust-secp256k1/pull/38 behind a feature gate using serde 1.0
* Clean up build process and various typos