LONDON (Reuters) -U.S. flights were slowly beginning to resume departures and a ground stop was lifted after the Federal Aviation Administration (FAA) scrambled to fix a system outage overnight that forced a halt to all U.S. departing flights. Here’s what we know so far: NUMBERS OF FLIGHTS: * A total of 4,314 flights were delayed within, into or out of the United States as of 1411 GMT, flight tracking website FlightAware showed, without specifying the cause of the delays * Another 758 flights within, into or out of the country were cancelled * Some 21,464 flights are scheduled to depart airpor…