FOR TUES ME The big red Northstar Blanket factory sign will be lit Wednesday for the first time in 50 years. The moribund riverfront building in downtown Minneapolis is being turned into loft apartments. The developers say re-lighting the sign shows the downtown riverfront is returning to life after decades of neglect. Minnesota Public Radio's Dan Olson reports. audio . . . (construction sfx) A few months ago the North Star blanket factory was uninhabitable. Brighton Develpment company partner Peggy Lucas says the 100 year old building's only permanent residents had wings. audio . . . this ceiling we're looking at now was f