by Richard CARTER Agence France-Presse TOKYO, Japan (AFP) — Virtual currency Bitcoin — or “digital gold” to its fans — has enjoyed a gravity-defying rise along with wild price swings, sparking fears it could be the latest financial market “bubble.” Bitcoin was worth just a few US cents when it began life in 2009 and last week changed hands for a staggering $17,000 despite having no central bank backing and no legal exchange rate. Here […]