ATHENS (Reuters) - Greek police fired teargas and stun grenades at protesters in central Athens on Tuesday when they tried to break through a barrier and reach visiting German Chancellor Angela Merkel. Tens of thousands of demonstrators defied a ban on protests, gathering in Syntagma square to voice their displeasure with the German leader, who many blame for forcing painful cuts on Greece in exchange for two EU-IMF bailout packages worth over 200 billion euros. ...