MADRID (Reuters) - Former world champion Garry Kasparov has announced his retirement from competition chess, according to Spanish media reports. Kasparov, 41, announced his decision after winning a prestigious tournament in the southern Spanish town of Linares for the ninth time on Thursday, state radio said. Kasparov, a leading member of a Russian liberal grouping known as Committee 2008, plans to devote himself to politics and to writing books, the radio said. Tournament organisers could not immediately be reached to confirm the reports. "I will play chess, because I like it a lot, but not professionally. I may play...