The fourth edition of the city-wide tastemaker event commences tonight, with Tucker Zimmerman and Kae Tempest headlining The Lexington and Camden’s KOKO respectively. A platter of venues including The Roundhouse, Barbican, Troxy, ICA, Outernet, The Garage, EartH, Fabric, Islington Assembly Hall and The Lower Third, in Tottenham Court Road, will…