Craig Taylor had a rough time when he first moved to London from Canada a dozen years ago. Someone tried to pick his friend’s pocket. A scam artist took advantage of him. Wandering around with an ancient A-Z street atlas, he often felt “lonely, duped, underprepared, faceless, friendless.” But something about the city got under his skin, so he resolved to push beyond his own experience and take its measure. Happily for us, the result is “Londoners,” a rich and exuberant kaleidoscopic portrait of a great, messy, noisy, daunting, inspiring, maddening, enthralling, constantly shifting Rorschach test of a place, as befits the book’s subtitle, “The Days and Nights of London Now — As Told by Those Who Love It, Hate It, Live It, Left It, and Long for It.”