Agence France-Presse: When Sigourney Weaver wrapped up her role as a feisty environmentalist in James Cameron’s blockbuster movie “Avatar,” the US actress teamed up with Cameron again — to save the Amazon. Once the movie was out in cinemas, Cameron, Weaver, and actor Joel David Moore — who played Norm in “Avatar” — travelled to Brazil on a fact-finding mission to see for themselves exactly what the impact of a project to build a massive dam on a tributary of the Amazon River would be. They …