Add new libsvn_client notification between transmitting deltas and 
finalizing commit. The final stage of commit may consume significant 
amount of time, especially if we have automatic packing someday.

NOTE: Subversion command line handling of this notification will come in 
later commits.

* subversion/include/svn_wc.h
  (svn_wc_notify_action_t): Add svn_wc_notify_commit_finalizing.

* subversion/libsvn_client/add.c
* subversion/libsvn_client/commit_util.c
* subversion/libsvn_client/copy.c
* subversion/libsvn_client/delete.c
* subversion/libsvn_client/mtcc.c
* subversion/libsvn_client/prop_commands.c
  (mkdir_urls, svn_client__do_commit, repos_to_repos_copy,
   single_repos_delete, svn_client_mtcc_commit, propset_on_url): Send 
   svn_wc_notify_commit_finalizing notification before closing edit.
* subversion/libsvn_client/import.c
  (import): Add URL argument and send svn_wc_notify_commit_finalizing 
   notification before closing edit.
  (svn_client_import5): Update caller.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1603388 13f79535-47bb-0310-9956-ffa450edef68