Macro declare_net_parameters

macro_rules! declare_net_parameters {
    {
        $(#[$s_meta:meta])* $s_v:vis struct $s_name:ident {
            $(
                $(#[$p_meta:meta])* $p_v:vis
                    $p_name:ident : $p_type:ty
                    = ($p_dflt:expr) from $p_string:literal
            ),*
            $( , )?
        }
    } => { ... };
}

A macro to help us declare the net parameters object. It lets us put the information about each parameter in just one place, even though it will later get split between the struct declaration, the Default implementation, and the implementation of saturating_update_override.