By Terje Solsvik and Gwladys Fouche OSLO (Reuters) -Terrified revellers at a gay bar in Oslo hid in a basement and desperately called loved ones as a gunman went on the rampage, killing two people and injuring 21 on the day the city was due to celebrate its annual Pride parade. Authorities said the suspect, a 42-year-old Norwegian citizen of Iranian origin, was believed to be a radicalised Islamist with a history of mental illness who had been known to intelligence services since 2015. The suspect will be subjected to a psychiatric evaluation in the coming days as part of the investigation, po…