Improve the use of forced eval

[ty-everett]

The library uses eval when using native implementation because ** is syntax error, but when we are forced to use eval the best way is to use it in a non-polluting way.

What I mean is that when this is used with rollup it makes it impossible to use some efficiencies

https://rollupjs.org/guide/en#avoiding-eval

Where eval is used, we should use this instead:

let globalEval = eval;
globalEval("(a,b)=>a**b");

Let me know any thoughts on this

[peterolson]

This should already be taken care of, since eval is only executed once to create the pow function.

See commit 2ca52567ae34e0f0d869cb10c78d234afa344cb5