WIP: 16C firmware hack for more memory

[brouhaha]

I now have trig functions (sin, cos, tan, and their inverses) working in the hacked 16C firmware. I haven't yet found a good place to store the angle mode. I'll have to allocate another "status register" to store it.

tan(90 deg) is giving a 9.99999999e99 result, but not setting the overflow flag.

I haven't yet hooked up the rectangular to polar and polar to rectangular functions.

I also put in factorial, but not Gamma(x+1).