     common_files: files in both dir1 and dir2.
     common_funny: names in both dir1 and dir2 where the type differs between
        dir1 and dir2, or the name is not stat-able.
     same_files: list of identical files.
     diff_files: list of filenames which differ.
     funny_files: list of files which could not be compared.
     subdirs: a dictionary of dircmp instances (or MyDirCmp instances if this
       object is of type MyDirCmp, a subclass of dircmp), keyed by names
       in common_dirs.
     Nc