Macro logicsim::generate_signal_getters

macro_rules! generate_signal_getters {
    ($signal:ident, $($rest:ident),+) => { ... };
    ($n:expr, $all:expr, $signal:ident) => { ... };
    ($n:expr, $all:expr, $signal:ident, $($rest:ident),+) => { ... };
}