On the revprop-caching-ng branch:  Some cleanup and doc update.
No functional change.

* subversion/libsvn_fs_fs/revprops.c
  (ATOMIC_REVPROP_GENERATION,
   ATOMIC_REVPROP_TIMEOUT,
   ATOMIC_REVPROP_NAMESPACE): Remove these obsolete defines.
  (Revprop caching management): Document the new intended behavior.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/revprop-caching-ng@1620208 13f79535-47bb-0310-9956-ffa450edef68