On the 'move-rtracking-2' branch: improve pool usage correctness and the
conversion of paths between internal style and storage style (the latter
using "." for the empty path).

* subversion/include/private/svn_editor3.h,
  subversion/libsvn_delta/editor3.c
  (svn_editor3_peg_path_dup,
   svn_editor3_txn_path_dup): New functions.
  (svn_editor3_node_content_dup): Duplicate the reference peg-path.

* subversion/libsvn_delta/compat3.c
  (svn_branch_instance_create): Duplicate the branch root path.
  (branch_map_update_as_subbranch_root): Correct the doc string.
  (svn_branch_instance_parse,
   svn_branch_instance_serialize): Don't use "local style" for storage, just
    convert between "" and "." directly.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1635169 13f79535-47bb-0310-9956-ffa450edef68