Democrats formally nominated Joe Biden for president on Tuesday, with elder statesmen and rising stars promising he would repair a pandemic-devastated America and end the chaos of Republican President Donald Trump.The convention’s second night, under the theme “Leadership Matters,” aimed to make the case that Biden would represent a return to normalcy.“At a time like this, the Oval Office should be a command centre,” former US president Bill Clinton said in a pre-recorded video. “Instead, it’s…