#92 tkchat - logging data change

[Larry W. Virden]

It would be useful if /msg and /memo messages were
logged uniquely in tkchat, so that someone could look
through the log output if they needed to locate the
whispers sent during an extended period of time of
distraction from the chat.

[Pat Thoyts]

Logged In: YES
user_id=202636

Added storage for memo messages to an mbox format file
~/.tkchat_msgs. Need to add a diaplay dialog to list and
show them.