Feature: `ThirdPartyDataref`, for datarefs that might not be loaded yet

[JDeeth]

The plugins I write are often to enhance an existing aircraft and work that aircraft's custom datarefs. As such they're not guaranteed to be loaded as my plugin might be loaded first.

I've written a ThirdPartyDataref class here: https://github.com/JDeeth/nb_bn2_tweaks/blob/c8284ad96a6457c783a94372b2f92f680fdf2835/src/dataref_command.rs#L10-L50

enum ThirdPartyDataref {
    NotFound(String),
    Found(DataRef<u32, ReadWrite>),
}

It starts off as NotFound and holds the name of the dataref it should connect to. When trying to get/set the dataref, a NotFound will first search for the dataref and transform itself into a Found if successful.

Would something like this be worth polishing up and moving upstream into this crate?

(I tried to genericise it beyond <u32, ReadWrite> but ran into inexplicable errors that went beyond my limited Rust skills..!)

[samcrow]

Yes, that sounds useful.

If you can include generic type variables for the data type and access in your enum, but implement the functions for u32 ReadWrite only, that will make it easy to fill in the rest later.