NEW YORK (Reuters) - Americans spent more in stores at the start of holiday shopping than a year ago, according to figures released on Saturday, but retailers' hopes for the key season were curbed as titan Wal-Mart cut its November sales forecast. Consumers lined up to grab early-bird specials as stores opened from 5 a.m. on the Friday after Thanksgiving, which is one of the year's biggest shopping days, known as Black Friday as it used to be the day retailers got into profit. Retailers now report profits throughout the year. Black Friday used to be the biggest shopping day...