By Robert Muller and Jason Hovet (Reuters) -Slovakia could treat the killing of two people outside a well-known gay bar in the capital Bratislava as an act of terrorism, a top prosecutor said on Friday, as investigators looked deeper into the shooting which has rattled the central European state. The killings, investigated as a possible hate crime although police have yet to determine its motives, have sparked outrage from politicians and rights groups, and prompted the president to call for reflection on the political climate in the country. Thousands gathered in downtown Bratislava later on …