A dog that gained attention 14 years ago when he emerged alive from a Missouri gas chamber has died.       Quentin’s death was announced by his owner, Randy Grim, founder of Stray Rescue of St. Louis. The mixed-breed dog had suffered a stroke.       Quentin was among eight dogs that were to be euthanized at the St. Louis pound’s gas chamber in 2003. Quentin’s owners surrendered him because they were moving to an apartment th…