Refactor in-memory diff so that "conflicts only" uses its own vtable.
Refactor in-memory diff so that "conflicts only" uses its own vtable.

* subversion/libsvn_diff/diff_memory.c
  (output_common_modified, output_latest, output_conflict): Remove
   code for conflicts-only.
  (output_conflict_with_context): New.
  (merge_only_conflicts_output_vtable): New.
  (svn_diff_mem_string_output_merge2): Use separate vtable for
   conflicts_only.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion