More --timeout improvements, especially for the receiving side: - The receiver now sends keep-alive messages to the generator when it is actively doing work and hasn't sent anything recently. This ensures that the generator won't timeout if the receiver is working hard. - The perform_io() code has improved keep-alive participation. - Allow the sender to send some keep-alive messages, which ensures that if it is in a lull, it can probe the socket.
Improve --timeout method to take into account all I/O that is going on. The receiving side also switches timeout handling from the receiver to the generator, which obviates the need for the sender to send any keep-alive messages at all (for protocol 31 and beyond). Given this setup, all keep-alive messages are now sent as empty MSG_DATA messages, with MSG_NOOP messages only being understood and (when necessary) acted upon to forward a keep-alive event to an older receiver. This is both safer and more compatible with older versions.
A major overhaul of I/O routines, creating perform_io(). Files-from data is now sent as multiplexed I/O so that it can mingle with any messages (such as debug output). Requires protocol 31. Protocol 31 no longer disables output verbosity in a couple instances that used to cause protocol issues. Got rid of MSG_* messages that have implied raw data that follows after them. We instead send a negative index value as a part of the raw data stream, which is guaranteed to be output together with the following data. This only affects the (in-progress) protocol 31 and the (self- contained) communication stream from the receiver to the generator. Added --debug=IO and improved --debug=FLIST. Some --debug=IO output requires --msgs2stderr to be used to see it (i.e. sending a message about sending a message would send another message, ad infinitum).