LONDON, Feb 2 : The dollar held on to gains on Monday as investors weighed what a Federal Reserve under Kevin Warsh might look like, while falling precious metals and oil prices kept commodity-linked currencies in check. A slide in commodities eased somewhat in Europe with gold recovering from its lows, but it still marked a nervous start to a week filled with central bank meetings and top-tier economic data, as well as an election in Japan. The yen was back on traders' radars, after Japanese