CHENNAI, April 5 -- For half-a-century, elections in Tamil Nadu meant one thing: a clash of the titans. On one side was playwright-turned-politician M Karunanidhi, who helmed the Dravida Munnetra Kazhagam (DMK) and became chief minister five times. And, on the other was J Jayalalithaa, an actor who rose through the ranks of the All India Anna Dravida Munnetra Kazhagam (AIADMK) to claim the chief minister's chair five times....