September 1421, 1995 best bets Best Bets/Rock Best Bets/ Rock By Neil Gladstone & Margit Detweiler Sept. 15: The Warmers/ The Make-Up.Act-Up Hall, 1318 Walnut St., 7 p.m. (all ages). A round of Dischord all-stars: Warmers guitarist Alec Mackaye used…