initial release

this implementation includes:

• BABE block production
• ability to sync blocks and state between multiple nodes (for both block-producing and non-block-producing nodes)
• SCALE encoding package
• polkadot-compatible trie implemenation
• preliminary command-line documentation
• preliminary polkadot-compatible RPC implementation

note that the wasm runtime it uses is the substrate test runtime for substrate@v0.6, which is not an official substrate runtime.