history: add exn handler and use milliseconds for timestamp
refactoring: add message-history% class and use it for sending received messages to receive messages
refactor: use msg-history for file transfers logging
error messages: start working on error reporting for incorrect file transfer IDs. (+ refactor rtansfers to rt-*)
error handling: check for incorrect transfer ID and show it in message history
bug: reference id's by their number instead of their position in list
Merge branch '4DA-master'