Align Mathics3 precedences with WMA's

[rocky]

Specific operator precedence values only have meaning in relation to other operator precedence values, so it is only the ordering between operators that matters operationally. However, any implementation in fact does this using specific orderable numeric values. In particular, we do, and WMA does as well.

It would simplify things if our numeric precedence values on operators more closely matched WMAs.

The WMA Precedence built-in function reports precedence values, so this is a publicly visible thing.

For the most part, I suspect we can just change most of the values listed in the operators.yml YAML file, and things will just work. However, there are also fewer than a dozen or so cases where some exception or code alteration may be needed.