BFI Lotte Reiniger's The Adventures of Prince Achmed was released a century ago in 1926. This stop-motion classic makes her "a key figure in the history of cinema". Starting out in the film business isn't always glamorous. In the silent era, aspiring German actress Lotte Reiniger began her career on an adaptation of a folk tale, The Pied Piper of Hamelin. But she wasn't in front of the camera. Her job was to handle the rats. Despite this inauspicious beginning, Reiniger would soon earn a place in cinema history. Just a few years after her rodent-wrangling experience, she was in the director's chair. That was extraordinary enough – in the 1920s, few women were given the opportunity to direct. But Reiniger's project was particularly innovative. Released a century ago in 1926, The Adventures of Prince Achmed is recognised as the world's oldest surviving animated feature film – despite what Walt Disney's publicists might prefer you to think.…