In the original game, the dome combination is not completely random;
only the first number is one that can be seen in the school (range 2-10),
two numbers are chosen from the range 11-15, and two are chosen
from the range 16-24. Presumably, this is done so that the code has
approximately equal difficulty for every game.
Until now, scummvm has generated completely random codes,
which results in some games having very easy codes (when most of
the numbers are below 10). Also, there's a 20% chance that
the last number is 25, which is never used in the original game.
