Baby, it was cold outside when Muntu Dance Theatre put on its 39th annual winter concert. But the atmosphere indoors was steamy, thanks to the synergy between dancers and audience. Last December’s show, “Spice It Up,” packed ’em in at the DuSable Museum of African American History. Two and a half hours of heart-rattling drumming and dance celebrated Mother Africa’s rituals—and, in the process, established a new ritual for the diaspora community here. Before the show started, audience members schmoozed. By the end, they were storming the stage, breaking out their own moves.