On the 'move-tracking-2' branch: switch the commit editor shim callbacks to
a single callback that can fetch the whole base state instead of having
separate functions for kind, properties and text. 

Also move the shim-related declarations from svn_delta_private.h to
svn_editor3.h to keep all editor3-related declarations together.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1619825 13f79535-47bb-0310-9956-ffa450edef68