Splash Screen appears to be working for non-fullscreen mode now.
Finally added in proper end game callbacks, so tally screen no longer
appears unless you actually finish the level via exit door. This was
fixed as part of making it easier to fix adn test the splash screen.
Fixed splash screen in full-screen mode by completely redoing how splash
screen works. It now appears for a given number of game ticks, and
whilst appearing rendering code will not render the UI. This is cleaner
and works more consistenly between fullscreen and non-fullscreen.

Fixes #33
Updated readme and removed .jar. Will be using a different form of .jar
distribution since keeping binaries in source control isn't exactly the
best idea.