Turner Classic Movies doesn’t usually offer films that were released in the 21st century – but as today is one of the “31 Days of Oscar” devoted to nominated and winning documentaries, tonight’s prime-time lineup begins with one welcome exception. It’s Al Gore’s An Inconvenient Truth, a lecture about the perils of ignoring climate change, released in 2006. And its facts and figures and images are alarming, weather or not you come to the film already persuaded…