By Denny Dyroff, Entertainment Editor, The Times Sabaton Music acts from Sweden are either sonically hard and very heavy – goth metal, death metal, doom and gloom – or light and very frothy – Abba, Ace of Base. Sabaton, which is headlining a show at the Fillmore Philadelphia (1100 Canal Street, Philadelphia, 215-309-0150, www.thefillmorephilly.com) on March 6 is the former. Sabaton is a metal...