Nonpareil status

[brouhaha]

I completed the 91 graphics. I also fixed the problems with trace mode on the 19C and (in development) 92, which also affected the 91 if the angle mode was GRAD. I'd forgotten to have the S0 flag output drive the KE input of the ACT key scanner, which the hardware uses to ensure that there's always a pseudo-keystroke available when the slide switches are read. This also fixed a problem where a financial calculation example on page 30 of the 92 owner's handbook was hanging.
The updates are in the github repo.
I need to do the graphics for the 92, and then it may be time for a new Nonpareil release.