Write _length_ bytes from _data_ to the file. If no I/O errors occur,
the complete _length_ bytes will be written (or queued for writing).
@param fp BGZF file handler
@param data data array to write
@param length size of data to write
@return number of bytes written (i.e., _length_); negative on error
Write _length_ bytes from _data_ to the file. If no I/O errors occur, the complete _length_ bytes will be written (or queued for writing).
@param fp BGZF file handler @param data data array to write @param length size of data to write @return number of bytes written (i.e., _length_); negative on error