Markeen - The candidate problem

Markeen has trouble with the combination of more-than-one-deep profiles and the scarcity of original levels. There are plenty of more-than-one-away tile placements for most tiles that would work perfectly fine but don't appear anywhere in the originals. The candidate scoring algorithm devalues (instead of deletes) not-found options once the depth is more than 1, but the starting list of candidates is taken from only the first present neighbor, usually the top. This isn't terrible, since a tile should have to be seen before next to all its immediate neighbors. It does perhaps get the probabilities of the final candidate list wrong, though. Biasing the selection toward the preferences of one side seems incorrect, so I'll have to see about changing that.