ORLANDO, Fla. — At 91 years old, William Shatner has seen entire eras of film come and go. But he still has his eyes on the future of science fiction. Shatner was an honored guest at this year’s Florida Film Festival, which hosted a screening of 1986′s “Star Trek IV: The Voyage Home,” followed by an audience Q&A on April 15. “A great science fiction story has its roots in reality,” Shatner said ahead of the event. “The setting is futuristic and imaginative and is somebody’s view of what the future will be,” adding that “the roots of the story are always dealing with the human condition.” Accor…