Somewhere tonight, across the country or across the sea, a singer, sitting on a stool on a pub’s corner stage, is belting out a Kevin McKrell song and the crowd is singing along. McKrell pioneered American Celtic music beginning in 1979 with his band ‘Donnybrook Fair’. The original trio’s 1982 album Tunnel Tigers remains a landmark of the form, with its blend of Clancy Brothers swagger and upstate NY attitude. Kevin McKrell is best known, though, for his indelible songs—classics like ‘Donegal’, ‘I Miss the Rain’, ‘Dublin Town’ and the eternal ‘All of The Hard Days Are Gone’—which, in addition …