LONDON, Feb 18 (Reuters) - Europe's major stock markets are seen mixed at the open of trading on Monday, according to financial spreadbetters, with some dealers expecting investors to take a cautious approach following the G20 meeting this weekend. Financial spreadbetters saw Britain's FTSE 100 ranging from down by as much as 5 points, or 0.08 percent lower, to trading unchanged at the open. They saw Germany's DAX ranging from down by as much as 3 points, or 0.04 percent lower, to up by