On the 'move-tracking-1' branch: start to transmit some moves to the repo
and store them as such in FSFS.
 
  Client side:
    + Make 'move URL URL' send a move to the RA layer.

  Network:
    + In RA-local (only), implement sending a move using the 'copy' method
      with copy-from-rev = -1.

  Server side:
    + In the repos layer, implement storing a move using the 'copy' method
      with copy-from-rev = -1.
    + Add a FS layer 'move' method.
    + Add a FSFS 'move' method, that keeps copy-id the same. (In all other
      respects it's still recorded as a 'copy' and a 'delete'.)

* subversion/libsvn_client/copy.c
  (path_driver_cb_func): Process moves as moves, and don't process deleted
    paths separately.
  (repos_to_repos_copy): Set the copy-from source revision to -1 for moves,
    and don't have path_driver_cb_func() processes those source paths.

* subversion/include/svn_delta.h
  (svn_delta_editor_t): Document that the editor can now support a 'move'
    operation, using the 'add' methods with copy-from-rev = -1.

* subversion/include/svn_repos.h
  (svn_repos_get_commit_editor5): Document that this editor supports 'move'.

* subversion/libsvn_repos/commit.c
  (add_file_or_directory): Handle copy-from-rev == -1 as a move.

* subversion/include/svn_fs.h,
  subversion/libsvn_fs/fs-loader.c
  (svn_fs_move): New function.

* subversion/libsvn_fs/fs-loader.h
  (root_vtable_t): Add a new method, 'move'.

* subversion/libsvn_fs_base/tree.c
  (root_vtable): Add a dummy (null) entry for 'move'.

* subversion/libsvn_fs_fs/tree.c
  (fs_move): New function.
  (root_vtable): Add it.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-1@1485309 13f79535-47bb-0310-9956-ffa450edef68