[DGD]network undo

[Felix A. Croes]

Since send_message() and send_datagram() are now always buffered
until the end of the thread, I had to change the way they worked
in 1.1.98:

send_message() now returns the number of bytes it could store
in the output buffer (which is 64K large).  It does <not> buffer
more than that, so if the return value indicates that only part
of the string was buffered, you'll have to re-send the remainder
of the string, later.  The kernel library has been adjusted to
simulate the old behaviour.

message_done() is now called whenever the output buffer empties,
not just when it empties the first time after send_message()
indicated that it could only sent a partial string.

send_datagram() can now only send one datagram per user object
per thread.  If you try to send more, the kfun indicates an error
by returning 0.

Regards,
Dworkin

List config page:  http://list.imaginary.com/mailman/listinfo/dgd