tools (stream): data modification on SatFile: - if `data_cb` is used and if it returns a not None value, it is used instead of the data read from the file. This allows data modification on the fly, useful notably for encryption - new `check_size_with_read` argument which check size on `close()` using amount of data actually read/written instead of file size. This avoid a warning when file is modified on the fly - added `closed` attribute