chatroom1: Simple client-server echo application. Server echoes whatever message client sends and then closes the socket.
chatroom2: Simple chatroom. Can support a variable number of users (currently set to 5). Broadcasts messages from one user to all users.
chatroom3: All the functionality of chatroom2 with the added capacity for private conversations between two users (user types @Username to message privately).
chatroom4: Adds friendship functionality. In order to have private conversations, users must be friends (to friend each other, users enter: #friendme @Username)