REEDSPORT — The Umpqua River Lighthouse, a guide for generations of mariners, will help a wave-energy company learn if it’s on the right course. Ocean Power Technologies, a New Jersey company that designs buoys to generate electricity, will install an antenna in the lighthouse’s museum to monitor a buoy it will place off the coast near Reedsport. Douglas County commissioners Wednesday agreed to allow the company to use upstairs space for free. The museum was once part of a Coast Guard station that operated the lighthouse. The Coast Guard earlier this year turned the lighthouse over to the county. The …