Exuberant presentations by local companies Saturday celebrated three American mentors of African dance. Performances by KanKouran West African Dance Company and Coyaba Dance Theater at Washington’s 25th annual DanceAfrica festival feted festival director Chuck Davis and the city’s Melvin Deal, both in their 70s. Also honored was KanKouran artistic director Assane Konte, 61, who moved from Dakar, Senegal, to Washington in 1978.