Fix nested maps

[Ketasaja]

Removes shadowing from generated code, allowing for events like:

event test = {
    from: Client,
    type: Reliable,
    call: ManyAsync,
    data: map { [
        map { [string]: boolean }
    ]:
        map {
            [boolean]:
            string[][][]
        }
    }[]
}

Ideally there'd be an integer suffix instead of _v_v_v_v_v_v_v, this is a quick fix to hold over until the rewrite.

[sasial-dev]

Oh. My. God - you are awesome, thank you for doing this!