Boilerplate files
Can click on numbers and see debug output on console, but have to click precisely on the black text, not the white around them, so need to have a square button behind number.
Have clickable box buttons for numbers now.
Now can click on numbers and have digits populate the number entry box.
Adding digit displays, haven't tested yet.  Lots of duplicate code with num entry box so maybe that could inherit from DigitDisplay.
The num entry box aligns, but needs to be more integrated with the display digit code instead of just aping it.
Setting the display digits works now.
Indicator turns green when solution is correct, red when wrong.