Oscar Cortes looked a bright spark after joining Rangers on loan from Ligue 1 RC Lens in January. The young Colombian winger, 20, was signed on an initial loan-to-buy deal after a €4.5m (£3.8m) move to France from local club Millonarios last summer. Nils Koppen was familiar with Oscar Cortes from the TransferRoom summit and alongside Mohamed Diomande and Fabio Silva, the new Rangers Director of Recruitment looked to have made a bright start to his Ibrox tenure with this January trio. But a frustrating injury sustained only seven games into his Rangers career, and subsequent surgery, has thrown…