Polkadot/Substrate PoC-1

The first in a series of Polkadot proof-of-concepts.

This is a co-release with the underlying blockchain engine Substrate, also PoC-1.

This includes a working PoS blockchain based on a PBFT PoA algorithm with an on-chain upgradable, Wasm-based state-transition subsystem, networking and a basic persistent trie. The runtime includes a secure random beacon based on collective coin-flipping and a hybrid referendum/delegated democratic governance system. It has a transaction queue, simple gossip transaction propagation between nodes and basic RPCs.

It doesn't yet include any parachain functionality or slashing.