Update py-decorator to 4.0.6:

4.0.6 Removed a file x.py accidentally entered in the tarball (2015/12/11)
4.0.5 Documented a quirk signaled by David Goldstein when writing decorators
      for functions with keyword arguments. Avoided copying the globals,
      as signaled by Benjamin Peterson (2015/12/09)
4.0.4 Included a patch from Zev Benjamin: now decorated functions play well
    with cProfile (2015/09/25)
4.0.3 Added a warning about the memoize example, as requested by Robert
    Buchholz (2015/09/25)

(wiz)