sim.app.pacman

This is a moderately faithful reimplementation of Pac Man, with a few 
differences and twists.  Major differences:

- No "scatter" behavior, though the ghost behaviors are otherwise fairly
  faithful.
- The Pac's animation is somewhat different
- No fruit

Major twists:

- You can have as many lives as you want.

- We enable multiple mazes.  Two by default are included.  Mazes are
  simple PBM files.

- We enable multiple pacs.  By default that's turned on.  Control the
  second Pac with the adws keys and the first pac with the arrow keys.
  You might try experimenting with subclasses of Pac to create AI pacs
  of your own (we've done that in-house).

