Generate long constants with separators

[boxdot]

Example:

Instead of

pub const INFINITE: u32 = 4294967295;

generate

pub const INFINITE: u32 = 4_294_967_295;

This would remove clippy warning in Rust.

Another possibility, would be to use #![allow(clippy:all)]. In the end, this is generated code and is not meant to be very readable.