LONDON (Reuters) - World shares gained on Tuesday as some investors held out hopes for a trade deal between the United States and China, even though they continued to raise tariffs on each other last week.Shares in Asia gained followed U.S. stocks higher on Monday, after U.S. President Donald Trump predicted a trade deal with China. European shares recovered to trader higher after opening lower.Automakers and Italian stocks boosted the pan-European STOXX index, which was up 0.3% by midday in..