LISBON (Reuters) - Portugal's opposition Socialists scored their biggest-ever electoral victory on Sunday as voters ousted centre-right Prime Minister Pedro Santana Lopes after only seven months in power, exit polls showed. Western Europe's poorest nation swung to the left in giving Socialist leader Jose Socrates an absolute majority in parliament needed to implement a platform the party said would boost the lagging economy. Analysts said the resounding win amid a large turnout was a welcome sign of stability for the nation of 10 million people. Socrates's government will be Portugal's fourth in three years. President Jorge Sampaio dissolved parliament...