By Sanjeev Miglani NEW DELHI (Reuters) – India’s prime minister is rallying his nationalist base as the world’s biggest democracy begins a general election on Thursday, but it has become tighter than anticipated, thanks to dwindling incomes for farmers and scarce jobs. Polls predict Narendra Modi’s Bharatiya Janata Party-led (BJP) alliance will just win a parliamentary majority, a sharp drop from his commanding mandate five years ago, when he vowed to turn India into an economic and military power. …