Flushed old READ-CHAR implementation in favor of new simple READ-CHAR and
complex READ-COMMAND which reads a telnet command into a single sequence and returns it. Not finished with READ-COMMAND yet. Also redid READ-CHAR, UNREAD-CHAR to use CL functions directly on stream rather than maintaining our own character unread mechanism. Will make PEEK-CHAR implementation much simpler too. Probably the READ-CHAR should become %READ-CHAR and then a new READ-CHAR which does command processing can wrap around it. Or different names perhaps, but the user shouldn't need to call READ-COMMAND and PROCESS-TELNET-COMMAND directly.