There are more ''poor me'' memoirs around than you could shake a stick at. David Millionaire Pelzer has a lot to answer for. It's got to the stage where I creep past the autobiography section in a bookshop in as inconspicuous a manner as possible, lest one of the heroic survivors actually reach out from the cover of their therapy-masquerading-as-book and hold me for ransom. Less offensively, wartime childhood memoirs look chirpily on, willing me to pick them up and take them home. They're nice an' all, but one is so often much the same as another.