Pointlessly pulls in the num crate

[omarandlorraine]

Other than skeptic, far and away the biggest contributor to the compile time here is num.

I see src/lib.rs seems to deliberately do extern crate num;, is this vestigial? It doesn't seem to do anything or go anywhere??

[mre]

Oh, I don't know. If it's not needed, let's remove it. 👍