From the southern tip of the continent to the northern edge, from Nigeria to Egypt and beyond, African art is rich, wild, ordered, magnificent, tranquil and irrepressible. For the first time in the history of contemporary art, 54 artists, one for each country in Africa, are presenting a piece of work in Paris this month. Two of these artists, Athi-Patra Ruga and Naziha Arebi, join Eve Jackson in the studio.