NEW YORK (AP) — In Questlove’s documentary “Summer of Soul” a musical flood, too long dammed up, is finally released. The movie is both a corrective to a lost history and a foot-stomping, soul-stirring party. It unearths some 40 hours of footage from the largely forgotten 1969 Harlem Cultural Festival. It drew together Nina Simone, Stevie Wonder, Sly and the Family Stone, B.B. King and many of the giants of gospel. For five decades, the footage mostly sat in a basement. “Summer of Soul” opens in theaters nationwide Friday and streams on Hulu.