WASHINGTON — Film director James Cameron may have another blockbuster on his hands. Federal officials are hoping Cameron can help them come up with ideas on how to stop the disastrous oil spill in the Gulf of Mexico, officials said today. The “Avatar” and “Titanic” director was among a group of scientists and other experts who met Tuesday with officials from the Environmental Protection Agency and other federal agencies for a brainstorming session on stopping the massive oil leak. The Canadian-born Cameron is considered an expert on underwater filming and remote vehicle technologies. “Avatar” and “Titanic” are the two highest-grossing...