#21 Enhance chat example

[Hanno Braun]

The chat example in its current state is useful for testing, however, it's not useful as an example that a new user could learn from.
The following must be done to change this:
* Refactor the code, both client- and server-side to be more clear.
* Document the code.
* Enhance the user interface. Right now, the user interface is rather crude and doesn't make a good impression to users.