* subversion/svn/conflict-callbacks.c (svn_cl__conflict_handler): Pass path_prefix to the file merge tool.
* subversion/svn/file-merge.c (svn_cl__merge_file): New path_prefix parameter. Display the file's name at the start of the merge, and add a nofication at the end of the merge indicating whether the file remains in conflict.
Add chunk editing support to the new internal file merge tool.
* subversion/svn/cl.h (svn_cl__merge_file): Add editor_cmd parameter to declaration.
* subversion/svn/conflict-callbacks.c (svn_cl__conflict_handler): Pass external editor command to merge tool.
* subversion/svn/file-merge.c (file_merge_baton): Add editor_cmd and config members. (merge_chunks_with_conflict_markers): New, factored out from existing code in merge_file_chunks(). (edit_chunk): New. (merge_chunks): Offer the option of editing either or both chunk versions and using the result in the merged file. (merge_file_chunks): New parameters editor_cmd and config, pass them through. (merge_file_chunks): Code from here was factored out to the new merge_chunks_with_conflict_markers() helper. (file_merge_output_conflict): Pass editor_cmd and config through. (svn_cl__merge_file): New parameter editor_cmd. Pass editor_cmd and config through via the file_merge_baton.