xstate 4.2.1 on Node.js NPM

📚 Lots of documentation updates: https://xstate.js.org/docs
💥 Added the .event property to State instances, so you can know which event caused the transition to the current State:

const lightMachine = Machine({ /* ... */ });

const currentState = lightMachine.transition('green', 'TIMER');

console.log(currentState.event);
// => { type: 'TIMER' }

👪 Fixed #269 by ensuring two things:
- Services invoked on the parent machine (which are alive for the lifetime of the machine, FYI) are successfully invoked when the machine is started
- Starting activities (such as invoke, which is an activity) should be executed before executing onEntry actions.