Preface ¶ I started this paper in 2013, and in 2015 sent it out for review to the people listed later on. After incorporating comments, I sent it to Rik Farrow, the editor of the USENIX magazine ;login: to see if he would publish it. He declined to do so, for reasonably good reasons. The paper languished, forgotten, until early 2018 when I came across it and decided to polish it off, put it up on