Make Addresses fields public

[David-OConnor]

So you can set things while leaving the rest default:

let addresses = Addresses {
    rf_channel: RF_CHANNEL,
    ..Default::default();
}

I don't think there's another way to do this currently without hand copying the pipe addresses etc.

[thalesfragoso]

The rf_channel field is actually checked in Addresses::new, and other code relies on that. So, we can't just make the fields public.

[David-OConnor]

You could check rf_channel later, and make the fields public. Addresses doesn't do much on its own; it could be classified as a config struct.

Without making this or a related change (there are several alternatives that don't involve making the field public, such as setter methods, alternative constructors that accept channel args etc; although I think what I proposed is the cleanest for application and this lib code), how would you handle this in application code?