Number-first input mode on latin square puzzles (Solo etc.)

[chrisboyle]

There have been a couple of requests for this, most recently from Nora Kischer-Browne in a Play review:

My only quibble is that some of the interfaces use unnecessary motions like selecting the box and then the number in Filling and Solo/Sudoku, when my favorite Sudoku-only app allows you to do the reverse, filling in multiple boxes with one number selection.

This would have to be an option, default off, as long as the other platforms don't change to this mode. It would involve starting to use the key state feature of KeyboardView.

I worry that it might be a bit cumbersome if you use pencil marks a lot (lots of long presses to add/remove them).