DUESSELDORF, Germany (Reuters) -Freezing rain in central and southern Germany grounded hundreds of flights and restricted train traffic on Wednesday as the weather service warned of slippery roads and heavy snowfall. At Frankfurt airport, 570 of the 1,047 scheduled arrivals and departures were cancelled, while 254 flights were scratched at Munich airport and a smaller airport in the southern city of Saarbruecken ceased operations completely. Timetables at Frankfurt’s airport showed only a very limited number of flights were still set to depart. “I’ve had nothing but stress since yesterday,” sa…