Refactoring.
Refactoring.
Make it possible to win the game.

The player needs to find the "endgame item" and bring it back to the
surface. That item spawns randomly once the player reaches a high
enough level. (Need to tweak this.)

Improved the way the hall of fame is printed.

Some refactoring along the way.
Tweak endgame knobs.
Different reason for end when quitting.
Document space bar.
Fix Invalid Command on arrow keys in emacs.
Refactoring.
Refactoring.
Refactoring.
Refactoring.