This patch changes the algorithm used for generating random puzzles.
It also increases the difficulty of the puzzles by adding 20 extra viruses.
For example, Level 20 puzzles have 104 viruses instead of 84 viruses.

Note: The original game has puzzles with at most 84 viruses.  It is possible
to add 4 extra viruses per level, withouth running into any problems.  However,
further increases will result in the game entering an infinite loop generating
some puzzles.  To further increase the number of viruses, a new algorithm is
needed.  The algorithm used in this hack does not have the same issue.

Verisons
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V1.0
Initial version.
This version adds 20 viruses per level, and keeps adding 4 more per level.
For example, Level 20 puzzles have 104 viruses instead of 84 viruses,
The highest position of viruses is increased by one row on Level 21--22,
and by two rows on Level 23--24 which should make them impossible to clear.
The number of remaining viruses does not show up until a virus is cleared,
and any number over 100 will be written incorrectly.