Dwindling crowds, a shortage of home grounds and a widening gulf between clubs. Thirty years on, the Singapore Premier League faces questions about its future.  SINGAPORE: The date was Apr 20, 1996. At Toa Payoh Stadium, Balestier Central were about to face Police FC in the opening round of Singapore's first professional football league, the S-League. “There were long queues to enter the stadium,” recalled local football blogger Ko Po Hui, one of the 2,400 in attendance.   The buzz had been