LONDON, Oct 9 (Reuters) – Shell lifted a force majeure imposed on exports of Bonny Light last month while prices for Angolan cargoes continued to ease due to higher shipping costs. * Shell announced the force majeure on Sept. 13 after one of two pipelines taking the key grade to the export terminal was shut down and said it was lifted on Oct. 8. * The issue has inflicted export delays of between 2 and 5 days and caused the export calendar to be reshuffled around four times, irking m