Version 0.3.0

• Send heartbeat pings to clients to detect dead connections and close them.
  Pings are implemented at the application protocol level (i.e not WebSockets).
• The wallet will now explicitly check for errors and responses before returning
  when sending a request.
• Max value ID requests will no longer respond with an IO error. However,
  applications may misbehave as this is the reserved ID for general messages.

Breaking Changes

• The network binary protocol now has a body type signifying the type of
  message. By decoupling from RPC, we can now send generic messages that don't
  expect a response.