Alive, he was a spy in purgatory on death row – neither executed by his Pakistani captors nor released to return home to India.In death, Sarabjit Singh, 49, has become the source of a tense verbal battle between South Asia's nuclear-armed rivals.After serving 22 years in a Pakistani jail for a confession-backed conviction for espionage and involvement in bombings in 1990 that killed 14 Pakistanis,...