[Feature request]: Enable rounding to zero

[GreenImp]

Feature request and related problem

As mentioned in the docs, the round() function always rounds half away from zero.

Sometimes we want to round towards zero instead:

// positive numbers
3.7   -> 3
4.5   -> 4
12.3  -> 12

// negative numbers
-2.9  -> 2
-3.5  -> -3
-65.2 -> -65

This was originally mention in #227

The Javascript Math.trunc() method achieves this.
And MathJs (The library used internally by this library) has a fix() method, which also does this, but has the benefit of also allowing you to specify the number of decimals.

Suggested solution

I propose that we enable a fix() function, which uses the MathJs fix() function, and also an alias for it of trunc(), so those familiar with that method can use it.

Alternatives

No response

Additional context

No response