Michael Gleason, the co-creator of Remington Steele and producer of such popular series as Diagnosis Murder and Rich Man Poor Man Book 2, died Friday at the age of 78. His death was confirmed on his Facebook page; no cause was listed. Gleason, a novelist as well as veteran producer, started as a writer for such 1960s series as Rawhide, Laramie, My Favorite Martian, The Big Valley and Peyton Place, continuing through the ’70s with Marcus Welby, M.D., Cannon, McCloud and Ric…