On the 'moves-tracking-2' branch: Add an Ev3-from-Ev1 shim for commit
editors. This compiles but is totally untested.

* subversion/include/private/svn_delta_private.h
  (svn_delta__ev3_from_delta_for_commit): Declare.

* subversion/libsvn_delta/compat3.c
  New file, implementing the above.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1609704 13f79535-47bb-0310-9956-ffa450edef68