[ Suggestion] Integrate `cpc`, the unit calc/converter

[Diablo-D3]

cpc is a unit calculator/converter written in rust, but it does not have the features a bc-like does (REPL, history, etc); you have the bc-like part of the equation, but lacks a strong unit conversion game.

I feel these two programs should learn to work with each other.

[pickfire]

Let's see what @probablykasper thinks.

[probablykasper]

Would definitely be cool, but I don't think I'll be dedicating time to adding new features anytime soon unfortunately