Display: Fixed up color scheme in the challenge mode so that it is once
again readable. Also created a mock server with timed events so the
protocol is observable in real-time. Tested minimally, but it works so far.
Changed the background image in display, and the color schemes that
went along with it. Also, modified the code to be more object-oriented
in the Display objects. Thus, all Display modes now have message bubbles,
not just the Challenge mode.