change Promises into async functions

[bartekleon]

We should consider changing Promises to async functions. The 'how it works' would stay the same with the increase of performance (really slight tho) and readability (huge)

[nicojs]

Sure, go ahead. Be sure to also take error handling into account.

doWork()
  .then(() => doMoreWork())
  .catch(err => handleError(err))
  .then(() => doEvenMoreWork())

Becomes:

try {
  await doWork();
  await doMoreWork();
} catch(err) {
  await handleError();
}
await doEvenMoreWork();