Optimized C library for EC operations on curve secp256k1.

This library is a work in progress and is being used to research best practices. Use at your own risk.

Features:

* secp256k1 ECDSA signing/verification and key generation.
* Adding/multiplying private/public keys.
* Serialization/parsing of private keys, public keys, signatures.
* Constant time, constant memory access signing and pubkey generation.
* Derandomized DSA (via RFC6979 or with a caller provided function.)
* Very efficient implementation.