*****SUPERNOVA-SIZED SPOILERS!***** The third and final season of the original “Star Trek” (1966-9) (TOS) is often unfairly maligned in fandom for its drop in quality from the previous two. Yes, it’s true that creator/producer Gene Roddenberry took his hands off the wheel, along with a revolving door of producer/writers, including Gene Coon and John Meredyth…