It’s not just a concert/album launch, it’s a homecoming.Fiddler Doug Lamey, a Boston-area native and a denizen of its Celtic music and dance community – particularly that of Cape Breton – for a number of years, will be at the Burren Backroom in Somerville on May 14 at 4 p.m. to officially mark the release of his second recording, “True North.”He has been living in Cape Breton