* Implement minmax for Range; Simplify range command
* Port random integer to enginep; New FromValue impl
Now, FromValue is implemented for Tagged<Range> to allow extracting args
into this type.
* Make sure range value extraction fails properly
The range endpoint extraction methods now return error instead of
silently clipping the value. This now makes `random integer ..-4` fail
properly since -4 can't be cast as u64.
* Port random decimal to enginep & Refactor
This added a way to interpret Range limits as f64 and a Primitive helper
to get its value as f64.
A side effect of this commit is that it is now possible to specify the
command bounds as true decimals. E.g., `random decimal 0.0..3.14` does
not clip 3.14 to 3.