Khan, Pakistani cricketer-turned-politician and chairman of political party PTI, addresses his supporters during an election campaign in KarachiISLAMABAD (Reuters) – Cricket hero Imran Khan's Pakistan Tehrik-i-Insaf party won a revote in an upmarket constituency of Karachi on Sunday, unofficial results showed, a day after gunmen killed a birthday party leader, atmosphere the stage for protests and counter-protests. Khan blamed the killing of Zara Shahid Hussain on the Muttahida Quami Movement (MQM) birthday celebration, which has a stranglehold on the town. Furious MQM leaders denied duty, condemned the killing and demanded a retraction from Khan. …