Add BLAKE2 compression function `F` precompile

Status history

1. Draft4 Oct 2016
2. ⋯Finaldate not observed

Abstract

This EIP introduces a new precompiled contract which implements the compression function F used in the BLAKE2 cryptographic hashing algorithm, for the purpose of allowing interoperability between the EVM and Zcash, as well as introducing more flexible cryptographic hash primitives to the EVM.