[svn] * retr.c (fd_read_body): Report the amount of data *written* as

[svn] * retr.c (fd_read_body): Report the amount of data *written* as
amount_read.  This is not entirely logical, but that's what the
callers expect, and it's not easy to change.

* ftp.c (ftp_loop_internal): Ditto.

* http.c (http_loop): Be smarter about assigning restval; if we're
in the nth pass of a download, simply use the information we have
about how much data has been retrieved as restval.

* ftp.c (getftp): Ditto for FTP "REST" command.

* http.c (gethttp): When the server doesn't respect range, skip
the first RESTVAL bytes of the read body.  Never truncate the
output file.

* retr.c (fd_read_body): Support skipping initial STARTPOS octets.