Britain's eurosceptic opposition leader backs EU but attacks Cameron

By Kylie MacLellan and Elizabeth Piper LONDON (Reuters) - The leader of Britain's main opposition Labour Party urged voters on Thursday to back a campaign to remain in the European Union "warts and all", but his appeal did little to conceal his lingering euroscepticism. Underlining the challenges for a referendum that is blurring Britain's traditional political divisions, Jeremy Corbyn spent more time attacking Prime Minister David Cameron, who is leading efforts to remain in the EU, than praisi