By Hamza Ibrahim KANO, Nigeria (Reuters) -Nigeria's presidential election was marked by long delays at some polling stations on Saturday, which did not deter large crowds of voters hoping for a reset after years of worsening violence and hardship under outgoing President Muhammadu Buhari. Africa's most populous nation is struggling with Islamist insurgencies in the northeast, an epidemic of kidnappings for ransom, conflict between herders and farmers, shortages of cash, fuel and power, as well as deep-rooted corruption and poverty. Reuters reporters at locations across the country saw a mixed ...