109.31.00

- Renamed `Reader.read_one_chuck_at_a_time_until_eof` as `Reader.read_one_chunk_at_a_time`,
  and added a new case to the `handle_chunk` callback.

  The name change is to reflect that one can stop early, before EOF.

  The new `handle_chunk` case allows one to specify the number of bytes
  that were read in the `Stop` case.

  Also, changed `read_one_chunk_at_a_time` to use `do_read` instead of
  just locking the file without unlocking it.  This allows subsequent
  read operations to read from the file.