title: Change Vim swap/backup/undo file name
body: <p>Is it possible to change the way Vim names its swap/backup/undo files? </p>
  
  <p>To avoid clutter, I've set options in my <code>~/.vimrc</code> to dump these files in <code>~/.vim/tmp/{swap,backup,undo}</code>; however, as I routinely edit files in different directories with the same name, I often end up with lots of otherwise indistinguishable files and Vim sometimes has trouble recovering. </p>
  
  <p>Ideally, I'd like to use the naming scheme that the persistent undo has (<code>%path%to%file.undo</code>) for all these auxiliary files; there's no obvious way to set it, but can it be done with <code>Buf{Read,Write}</code> macros?</p>