JACKSONVILLE, Fla. — Once touted by Southern Baptist leaders as the nation’s next great African-American preacher, Darrell Gilyard has resigned from his fifth church over charges of sexual misconduct — this time with underage girls. Dogged for 20 years by dozens of allegations of extramarital sex with parishioners, Gilyard, 45, resigned Jan. 4 after 15 years as pastor of Shiloh…