FOREX-Dollar touches six-month high ahead of GDP and Fed tests

* Dollar index holds firm, touches fresh six-month peak SYDNEY/SINGAPORE, July 30 (Reuters) - The dollar touched a six-month high against a basket of major currencies on Wednesday, holding firm ahead of a Federal Reserve policy decision and U.S. gross domestic product data due later in the day. Dollar bulls are holding out hope that the U.S. economy has rebounded in the second quarter from a ...