GitLab

Relocate code to set the cell value as last remaining draft state. It
was noticed that this code would otherwise trigger multiple times which
results in unneeded updates.

The `isDraft` function caused problem when events started to cascade and
updates were triggering re-evaluations of "the only value" of one type
in a row. And then set a wrong cell to the value. This patch omits the
problem by making sure that the cell with the set value is the only
remaining cell with the value and otherwise n+1 cells with this value
exist.

This change gets rid of a forEach loop in the dependency verification
process.

This minor project was just to explore if it's possible to solve Sudokus
event based and I think, I can say yes. There is room for improvement
but it basically works quite fine.