FELIX ONUAH and MACDONALD DZIRUTWE NIGERIA'S ruling party candidate, Bola Tinubu, was declared president-elect of Africa's most populous nation in the early hours of Wednesday after a weekend election that the main opposition parties have disputed. Tinubu, a former governor of Lagos state, will take over leadership of a country grappling with Islamist insurgencies in the northeast, armed attacks, killings and kidnappings, conflict between livestock herders and farmers, cash, fuel and power shortages, and perennial corruption that opponents say Buhari's party has failed to stamp out, despite promises to do so. The Independent National Electoral Commission (INEC) said Tinubu garnered…