The clients need to be able to know of the following happenings:

1. Their connection has been rejected by the server
2. Another user has joined/dropped from the session
3. The server wants to tell them of an error
4. A user is sending a chat message
5. A user has drawn something
6. A user did an UNDO on something

SRVE - Server error. Rejection, drop, server quitting, etc. Format:
    SRVE: Message string

SRVM - Server message. New user, lost user, etc. Format:
    SRVM: Message string

HELO - User is joining the server. Format:
    HELO: username

QUIT - User is quitting the server gracefully. Format:
    QUIT: username

RECT - user is drawing a rectangle. Format:
    RECT:msgid:username:startX:startY:height:width:color:fill(y|n)

POLY - user is drawing a polygon. Format:
    RECT:msgid:username:color:fill(y|n):numpoints:x1:y1:x2:y2:...

TRIA - user is drawing a triangle. Format:
    TRIA:msgid:username:x1:y1:x2:y2:x3:y3:color:fill(y|n)

LINE - user is drawing a line. Format:
    LINE:msgid:username:startX:startY:rise:run:color

QUAD - User is drawing a quadratic curve. Format:
    QUAD:msgid:username:x1:y1:x2:y2:ctrlx:ctrly:color

ELIP - User is drawing an ellipse. Format:
    ELIP:msgid:username:startX:startY:height:width:color:fill(y|n)

TEXT - User is drawing text. Format:
    TEXT:msgid:username:startX:startY:size:color:font:text

IMAG - User is inserting an image. Format:
    IMAG:msgid:username:startX:startY:height:width:URL
Note here that URL can be either a global URL, in which case we would download the image off the Internet, or just a filename, in which case the users would connect to the client that chose the image p2p and request a download.

UNDO - User is undoing an action. Format:
    UNDO:msgid:username:undoid
undoid corresponds to the id of the message we want to undo.

CHAT - User is sending a chat message. Format:
    CHAT:username:text