Added some cleanup/handling to users and made some helper functions.

Certain functions on the client can now be called from the chat by putting / first. Functions that can be called are in a whitelist 'run_func' switch statement.
All users get notified when another user has connected.
Server watches for user disconnects, and removes them from list, freeing up their username for a future logon.

System can now send messages without a <user>: prefix.
Username input for chat now removed. Chat styles changed to rgba to show what's underneath.
Client chat message helper written for easier logging to chat.
Users now can be looked up on the server easily by socket with get_user_by_socket(socket).

Object prototype extended with find. ** Use Sparingly, will be slow on large objects.