By Denny Dyroff, Staff Writer, The Times   “Defending the Caveman” is one of those shows that keeps coming back. No matter how many times the one-man show visits a city; it never seems to hit a saturation point. The actor in the show could come back out for a final bow, exclaim “I’ll be back” and be totally telling the truth.     The wildly popular show was written by Rob Becker...