Log messages in/out of the session to a file, if the file is in a directory
other than current, #log will try to create the last layer of directory for you.
Suggestion: always use an empty #log command to stop previous log event, except
                  for multiple logs (since 1.83d1)
Example (multiple logs support since version 1.83d1):
#log 1.log                  <== #OK. LOGGING..... (RAWMODE=0)
#log 2.log +               <== #OK. LOGGING..... (RAWMODE=0 APPEND) -- log appended to file
#log ?                        <== #FILES BEING LOGGED: 1.log, 2.log.
#log 1.log -               <== #LOG FILE "1.log" IS NOW OFF.
#log                           <== #OK. ALL LOGGINGS TURNED OFF.
#log 1.raw 1               <== #OK. LOGGING..... (RAWMODE=1) -- logs TELNET sequence as well
#log 2.raw 1+            <== #OK. LOGGING..... (RAWMODE=1 APPEND) -- guess ;-)