Twitter continues to be in for a bumpy ride. On top of a plummeting share price and struggles to attract new users, four of the company’s top executives are departing: product chief Kevin Weil, head of engineering Alex Roetter, Katie Jacobs Stanton, VP of global media, and Jason Toff, the general manager of Twitter’s Vine unit.A source familiar with the situation said Weil, Roetter and Stanton were leaving of their ...