Generalize typing of numbers

[Veljko Lipovac]

The goal is to replace the usage of pp.numbers with numbers.Real using the standard lib numbers from Python.
The reason is to increase the coverage of precision types, see example below:

With
pp.numbers = Union[int, float]
we get

[Veljko Lipovac]

I stumbled upon an issue with mypy (surprise). It does not support this built-in package.
There is/was an extensive discussion on their side python/mypy#3186.

Since this issue is not that crucial, you might want to consider closing it until it pops up or some compatible solution is found.

[Omar Duran]

Thanks @vlipovac. Since this issue doesn't deal with anything essential, I'm closing it for now.