WIP: 16C firmware hack for more memory

[brouhaha]

Woo-hoo! The new long division code is working! Now f MEM is essentially instantaneous in all cases. The original 16C code, even without memory expansion, had a noticeable delay for small word sizes unless a program was using up much of the RAM.

I know writing a routine like this would be trivial for some of the expert Nut microcode programmers that have been writing new modules for the 41C, but despite having written the first open-source microcode-level simulators for HP calculators, and spending thousands of hours studying HP's microcode from various models, I haven't actually written all that much of it. For me, this seems like an accomplishment.

In the original 16C code that did the division by repeated subtraction with no shift, the inner loop was six words. I replaced five of those six words with a gosub to the new patch, and three nops. The patch routine is 37 words.

The 16C ROM was really packed in tight, so two of the patches I've had to make only fit in an expanded ROM space. That's a total of 42 extra words so far. It shouldn't be a problem in simulators if they've reserved enough room for the 15C ROM (second R2D2 chip with ROM from 0x2000 to 0x37ff).