OUT/Ephemeral: more refactoring

o enhance several coments for clarity/directness/usefulness
o provide some (questionable approach) __doc__ strings for various stuff
  (instead, perhaps we should be using functools wrappy things?
  awkwardly, we can only use them some of the time in the case of
  EphemeralTransformer -- as it is sometimes a decorator and sometimes
  a pure generated function (depending on whether there is a become()
  in the dict ... or in any of the bases, sort-of).
o Break up DescriptorWrappersInstaller (it also contained pointlessly
  nested classes) and rename all sorts of poorly and/or too cleverly
  named crap.
o In what is now EphemeralRealMeProperty (formerly real_me_wrapper),
  route through functional API where we've made one, rather than
  mucking around directly with datastructures.

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>