[vxxabrnf] Calculator

Let's improve the standard four-function calculator with modern technology. Instead of just one register of Memory, absurd in these days of gigabytes and gigabytes of RAM, one can have ten memory registers, or even better, ten stacks. Definitely add the exponentiation (power) operator y^x. And for that you get Exp and Log for free. Sine, Cosine, Arctangent, Scaled Complementary Error Function, Inverse Error Function, Log Gamma, smallest prime factor, remainder