Macro bit_struct::enums

macro_rules! enums {
    (
        $(
        $(#[doc = $struct_doc:expr])*
        $(#[derive($($struct_der:ident),+)])?
        $enum_vis: vis $name: ident $(($enum_default: ident))? {
            $(#[doc = $fst_field_doc:expr])*
            $fst_field: ident
            $(,
                $(#[doc = $field_doc:expr])*
                $field: ident
            )* $(,)?
        }
        )+
    ) => { ... };
}

Create enums which have convenient TryFrom/From implementations. This makes using them with the bit_struct macro much easier.