JOIN works, PART appears to work

Had to redo the part_room() method on the Server class. The
implementation was wrong. Was able to use older code to fix it. JOIN now
works to join a room, PART appears to work to part a room. Odd bug while
testing multiple clients at the same time (probably from clients having
the same IP addr). If you start two clients, and JOIN with one of them,
both will get the server response to join, and open a new tab for the
chat room.