OSLO/BOGOTA (Reuters) - Historic closed-door talks between Colombia and Marxist rebels began on Wednesday in Norway after FARC rebel and government negotiators arrived secretly in Oslo in a bid to end almost half a century of armed conflict, Norwegian officials said. Colombia's President Juan Manuel Santos is betting a decade of U.S.-backed blows against the Revolutionary Armed Forces of Colombia (FARC) has left the group sufficiently weakened to seriously seek an end to the war after so many failed attempts. ...