clear out an old popt context before starting a new one.

  source transer, complain and exit.  This can help to find option
  problems were an arg to an option turns into a local-source arg,
  and the real remote-source arg will now get rejected rather than
  attempting to find a file with a colon in its name.
- We now support the ability to specify more than one remote arg using
  the ":FILENAME" idiom for additional remote filenames.
- If the --protect-args (-s) option was specified, we send just the
  "--server -s" options to the remote rsync when it is starting, and
  then the real args are sent over the socket.

- Renamed read_filesfrom_line() to read_line() and added args to allow
  the caller to control how it works.
- Added a new function, read_args(), that reads args from a file
  descriptor (using read_line()) and expands any wildcards in them.
  This function has relocated daemon code (from clientserver.c) and
  is also used by the new --protect-args (-s) option.  The new code
  also got rid of an extra strdup() that wasn't needed.

  number of remote args.
- We now exchange a "VERSION.SUBVERSION" value in the initial @RSYNCD
  message.  This is backward compatible with pre-protocol 30 rsyncs,
  and fixes a problem where rsync daemons weren't checking if they were
  speaking a compatible pre-release protocol.
- Moved the protocol-handling code (which was in two places) into a new
  function:  exchange_protocols().
- Protocol 30 now sends/receives the daemon args using NULLs as a separator
  rather than a newline.
- Moved the arg-reading code into a new function in io.c:  read_args().

other esoteric needs.

one instance inside the copy hierarchy.  (Used to fail with protocol 29
or --no-ir.)

file-entry values affected by HLINK_BUMP() stay put.

- Talk about how inc_recurse affects -H.
- Mention --no-inc-recursive and --no-ir options.

the generator.

- Incremented SUBPROTOCOL_VERSION to 7.

the code to use the structures and functions calls.

- Tweaked a {read,write}_varint30() call set that didn't need to be "30".

to support 2 sizes of key (32 and 64 bits), and to have a non-allocating
option for the find routine (returning NULL for no match).

all the time-preserving semantics into preserve_times.