Support new sudokuwiki.org string definition

[adjeiv]

Refs #56 Modify the 'allDigits' string to use the new definition, which encodes candidate information.

Currently, this only uses the 'innerPencil' markings, as these are what are populated by default when using the auto-calculate candidates function. Further, this ignores the hide pencil markings setting, but am happy to change this to only account for candidates when pencil markings are being shown if desired.

Tests cover empty grids with no candidate information; auto-calculated candidates; a mixture of candidates, givens, and solved clues; a mixture of candidates, givens, solved clues and cells with no candidate information.

[grantm]

Thanks for this! I hope to get a chance to review this in a week or so.

[adjeiv]

Friendly bump on this, in case you’ve had a chance to take a look!