GRAINS-Corn drops as rating points to bumper U.S. crop

* U.S. corn ratings rise in latest week * CBOT November soybeans pare losses after contract low * Short-covering lifts wheat (Adds closing U.S. prices, analyst comment on soy and wheat) By Rod Nickel Aug 26 (Reuters) - Corn futures fell on Tuesday with the U.S. crop reported in the best shape in two decades,[...]