Idaho-KGRC Grangeville, Buffalow Hump (cleanup/fix)

This add-on updates and fixes the KGRC Grangeville airstrip in Microsoft Flight Simulator. It includes corrections to the existing airstrip and introduces an additional fictional strip accessible at parking spot 4. Compatibility with certain scenery libraries is required for full functionality. The update aims to offer an improved and expanded experience for users flying in this region.