Fix toFraction and make use of it

[Rudxain]

The function should return the smallest fraction that when converted to Number yields exactly the same value as the original input, but some inputs cause it to loop too many times and return a bogus fraction. After fixing the bug, I plan on using it in Math.gcd to preserve precision of computations, and Math.factorize to get negative exponents

[Rudxain]

It already works now, but some numbers get converted to bogus fractions