THINGS TO DO:

* add error checking when reading map file

* check that the scheme file exists before passing to Guile

* add some way for the user to check on the shields level and energy
  level, so the robot can somehow respond to these conditions.


THING DONE:

* clean up the code so I don't use so many globals!  Try to pass the
  globals as args to the functions instead. [ok.  now the robot's
  position, etc. and the map information are shared globally ONLY
  BETWEEN api.c and main.c.  this is acceptable to me, as there is no
  way I can pass this information to the robot api, since the robot
  api is called through Scheme, not my program directly.]

* Add code to stop the game when robot takes too much damage or runs
  out of energy.
