GARDINER, NY-A 30-year-old gelding you surely never heard of who never did anything that special on the racetrack is scheduled to be put down Friday at his home, the Thoroughbred Retirement Foundation farm at the Wallkill Correctional Facility in upstate New York. It happens. They all get old and, for Renaissance Bob, it is his time. This is not pressing news. Far from it. But it will be a sad, bittersweet day for me. I saved Renaissance Bob's life, plucking him out of a kill pen on Nov. 23, 1998...