Three decades after seizing power in a military coup, Muhammadu Buhari has became the first Nigerian to oust a president through the ballot box. br br And so far at least there is celebration rather than unrest on the streets.br br As the scale of this weekend’s electoral landslide became clear, Buhari’s opposition party said that incumbent Goodluck Jonathan had called his victorious rival to concede defeat. br br That should ease tensions.br br Post-election violence in 2011 when Buhari, a Muslim northerner, last challenged Jonathan, a Christian southerner, left some 800 people dead. br br He has now comfortably beaten Jonathan whose perceived slow reaction to the kidnapping of more than 200 schoolgirls last April caused widespread anger, fuelling a public appetite for decisive military action against Boko Haram Islamists from a strongman such as Buhari.