(Refiles to correct day of week in first sentence to Thursday ) By Scott DiSavino NEW YORK, Feb 25 (Reuters) - U.S. natural gas futures on Thursday dove to within cents of their lowest level since 1999 as shale drillers pumped record amounts of the fuel and winter heating demand wilted under the warming effect of the El Nino weather pattern. Gas stockpiles are near record levels as homes and businesses haven't had much of a reason to keep heaters burning in recent months. A si
