Pattern (a.k.a. nonograms, paint-by-numbers)
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Fill in the randomly-generated picture by using the clues.
The numbers indicate the lengths of runs of black squares
in the row or column they are in.  

E.g. 2 3 indicates that there is a run of two black squares
before a run of three black squares somewhere in that 
column.  Somewhere in between them must be a run of white
squares but we need more clues to figure out where they 
are.

A-click to mark a square black.  
B-click to mark it white.
Y-click to mark it as unknown (grey).
