Module orderbooks

Structs

• BidAsk
  A bid or ask, depending on context
• BidAskUpdate
  Update to a price point for bids or asks
• Orderbook
  Orderbook containing a Vec<BidAsk> for each of bids and asks
• OrderbookMessage
  Message for an orderbook snapshot
• OrderbookUpdateMessage
  Orderbook update message containing all updates and the expected checksum of the final book