WIP: 16C firmware hack for more memory

[rprosperi]

For the stat. register locations, I think default .0-.5 make the most sense. These are out of the way of the 'normal' registers for everyday use but still easily remembered as 'same but with dots' as the normal 10/11/34. And I also think adding a ΣREG function, so the user can move them if needed is a good idea, flexibility is always a good thing.