Changed --stats implementation to work without -v in only these two

Changed --stats implementation to work without -v in only these two
situations:
    1. the client is the receiver of files.  Can't do it otherwise yet
	because without -v the bytes written from the sender's generator
	process will not be counted.
    2. both the remote and local protocol versions are >=20.  I did not
	change the protocol version yet because it is such a minor change
	that it isn't worth it, although I did test it with the protocol
	version set to 20.
If neither of the situations hold, it prints a message saying to use -v.