KINSHASA (Reuters) -Democratic Republic of Congo President Felix Tshisekedi was sworn in for a second five-year term on Saturday after a landslide victory his opponents have refused to recognise due to widespread irregularities over the December general election. Authorities have acknowledged there were issues but dismissed allegations the vote was stolen. The fractious standoff echoes previous electoral disputes that fuelled unrest in Africa's second-largest country, with protests breaking out in two eastern cities.