NEW YORK (Reuters) - Stock index futures edged lower on Tuesday as investors looked to take profits following an extended rally and as they waited an onslaught of earnings and data. On Monday, the S&P 500 index closed slightly lower, ending an eight-day run of gains. However, the index remained above 1,500, suggesting there was still support for the market. Investors poured $55 billion in new cash into stock mutual funds and exchange-traded funds in January, the biggest monthly inflow on record, research provider TrimTabs Investment Research said. ...