Is Ted Leo the best songwriter of his generation? That wasn’t a bad question to ask yourself last night at the B Side, where the indie rock staple showed up for a short, early-evening solo gig. With no stage to speak of other than a huge oriental rug, backed only by an amp, and encircled by a thick ring of adoring fans a spit’s distance from the man himself, Leo once again proved he’s a presence without his backing band, the Pharmacists.