By Hereward Holland Kampala – Ugandan President Yoweri Museveni accused the opposition on Tuesday of exploiting a dispute between his government and the leaders of an ancient kingdom to foment last week’s deadly riots. Local media say at least 21 people were killed in two days of street protests that convulsed the capital Kampala and other towns in the country’s central region. In comments to parliament, Museveni asked why Kizza Besigye, a former ally who now…