New user cannot see old content

[Robert McCoy]

If a new user connects to an existing room they do not get the existing contents of the textarea.

A simple solution for this until we turn to a database solution is:

New user connects to a page -> existing user is notified -> existing user emits a new message with their code -> server emits a new message to the new user with other users code -> new user receives the code.

This will follow a similar architecture to the enhancements relating to notifying a new user of new connections.

We would also probably want to implement a wait screen on the textarea until that code is received as well.