About 117,700 people in Hong Kong signed up online for the voluntary Covid-19 testing scheme in the first five hours of registration on Saturday, with the city expecting 18 new infections.Secretary for the Civil Service Patrick Nip Tak-kuen, who is coordinating the programme, called on the public to join as registration opened at 7am. Nip said it could help the government gain control of the Covid-19 crisis without need for further drastic social-distancing measures.More than 140 testing sites…