NEW DELHI (Reuters) - Grids supplying electricity to half of India's 1.2 billion people collapsed on Tuesday, trapping coal miners, stranding train travelers and plunging hospitals into darkness in the second major blackout in as many days. Stretching from Assam, near China, to the Himalayas and the northwestern deserts of Rajasthan, the outage was the worst to hit India in more than a decade and embarrassed the government, which has failed to build up enough power capacity to meet soaring demand. ...