- Set max_map_size based on the current file's block size (so that
  map_ptr() is more efficient with large blocks).

of the unrelated MAX_MAP_SIZE.

- Improved the warning if a batch option gets sent to the server.

without first transferring the batch file.

need the character buffers and so that it properly removes the
hostname from the destination arg.

is now fully set before the generator forks).

calling local_child().

suggested.

finish_transfer() so that it only gets output when we're actually going
to rename the file.