Linwood Scott III climbs two-story tobacco cropping machines with real agility and apparently no thought to falling. The sixth-generation tobacco farmer is proud of his machinery, upgraded 20 years ago and therefore relatively new. He delights in every tool and accoutrement of the cropping, curing, and baling process: every trailer, every sawed-off school bus that pulls those trailers, every conveyor belt, every one of his 200 small curing barns.Scott, in his early fifties, is from Lucama, North