On the 'move-tracking-2' branch: Add flexibility and verbosity in handling merge
conflicts in 'svnmover'. Make the merge have lenient "best guess" behaviour for
many potential conflict cases such as add-vs.-add (where the added content is
the same).

* subversion/svnmover/svnmover.c
  (merge_conflict_policy_t): New.
  (element_merge): Add flexibility and verbosity in handling merge conflicts.
  (branch_merge_subtree_r): Use a minimally strict, compile-time constant policy.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1634881 13f79535-47bb-0310-9956-ffa450edef68