for consistency, refactor the single file merge code to use the same callback    functions the rest of the merge code uses.
for consistency, refactor the single file merge code to use the same callback   
functions the rest of the merge code uses.

* subversion/libsvn_client/diff.c
  (svn_client_merge): move initialization of the merge baton up and pass it 
   in to do_single_file_merge as well as do_merge.
  (do_single_file_merge): take a merge baton as an argument, remove all the     
   arguments that come in as a part of that baton now, and call 
   merge_file_changed and merge_props_changed instead of reimplementing them 
   here. 
  (merge_props_changed): only call svn_wc_merge_prop_diffs if there are some 
   elements in the regular_props array.  this is unrelated to the other stuff 
   in this commit, but i noticed it while i was here.

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