Add Promises/await support

[egormalyutin]

Added function deasync.await, that is like await in async function, but works in sync function or global scope.

function sleepAsync(time) {
	return new Promise(function(resolve, reject) {
		setTimeout(function() {
			resolve()
		}, time)
	})
}
async function trim(str) {
	await sleepAsync(2000)
	return str.trim()
}

console.log(deasync.await(trim('       hello       ')))

[SnirBroshi]

The throw inside the catch won't really throw outside

[papb]

Suggested change

	done = false;
	result = undefined;
	pr
	.then(function(r) {
	done = true;
	return result = r;
	})
	.catch(function(err) {
	done = true
	throw err
	})
	deasync.loopWhile(() => { return !done });
	return result;
	done = false;
	result = undefined;
	error = undefined;
	pr
	.then(function(r) {
	done = true;
	result = r;
	})
	.catch(function(err) {
	done = true;
	error = err;
	})
	deasync.loopWhile(function() { return !done; });
	if (error) throw error;
	return result;

[SnirBroshi]

What about errors what are falsy? for example Promise.reject(0) or Promise.reject(undefined).
This still would no throw an exception

[papb]

@NotWearingPants I forgot that those rejections are technically possible. Indeed to cover that it would be better to use a didThrow variable instead.

[loynoir]

deasync.await = p => deasync((cb)=>p.then(x=>cb(null,x),e=>cb(e,null)))()

> deasync.await(import('some-esm-module'))
[Module: null prototype] {
...