A quarter century ago, a North Philadelphia choreographer named Rennie Harris founded the company Puremovement, which all these years later has become oldest touring hip-hop dance company in the country. FirstWorks brings Rennie Harris Puremovement to the Vets for a repertory performance that is sure to be energetic and impressive. It’s part of a big weekend for dance in Providence, since this event coincides with Brown’s 27th annual Rhythm of Change Festival. This year the university’s festival of African Diasporic performance draws artists from as far away as Mali and Senegal. On Saturday morning Harris will be involved with a follow-up breakfast conversation with several other choreographers and hip hop scholars.