Occasionally a producer or writer who is known primarily to music insiders suddenly emerges with a calling card that puts the wider world on notice. For Blue May , that card is Lily Allen ’s “West End Girl,” an astonishing album that may not just be one of the year’s best but be thought of as one of the decade’s best, when these 10 years are all said and done. Whether it registers as a commercial blockbuster or not, it is certainly as truly buzzy as a record gets. And if most of the chatter is