By Saurabh Sharma PRAYAGRAJ, India (Reuters) – A six-week Maha Kumbh Mela or Great Pitcher Festival begins in India on Monday, a Hindu sacred event that will be the world’s largest gathering of humanity as it showcases religion, spirituality, tourism and crowd management. More than 400 million people are expected in the northern city of Prayagraj in Uttar Pradesh state over the course of six