Princeton University has reached a settlement with heirs to the A&P grocery fortune, allowing it to keep the bulk of a fund worth hundreds of millions of dollars, in a move which brings to an end a long-standing dispute. In 1961, when Charles and Marie Robertson gave Princeton a $35 million gift endowment, they directed that the money should be used to educate graduate students for careers in government. But in a lawsuit filed in 2002, the Robertsons’ descendants claimed that Princeton was misusing the gift, spending it on training students for a broader range of careers.