code: public long[] fileProgress() {
          int64_vector v = new int64_vector();
          th.file_progress(v);
          return Vectors.int64_vector2longs(v);
      }
docs: This function fills in the supplied vector with the number of
  bytes downloaded of each file in this torrent. The progress values are
  ordered the same as the files in the torrent_info. This operation is
  not very cheap. Its complexity is *O(n + mj)*. Where *n* is the number
  of files, *m* is the number of downloading pieces and *j* is the
  number of blocks in a piece.
  
  @return the file progress