Various venues, EdinburghThis thrilling festival features Ibrahim Mahama's unmissable meditation on the railway that plundered Ghana, nuclear attack relics, and a stunning Chris Ofili tapestry Time is a return ticket in Ibrahim Mahama's Songs About Roses, which is on display at the Fruitmarket Gallery, far and away the best show in this year's Edinburgh art festival. Mahama draws young men lugging rails in detailed y…
