Write nbdkit plugins in Rust

nbdkit is our flexible, pluggable NBD server. See my FOSDEM video to find out more about some of the marvellous things you can do with it.

The news is you can now write nbdkit plugins in Rust. As with the OCaml bindings, Rust plugins compile to native *.so plugin files which are loaded and called directly from nbdkit. However it really needs a Rust expert to implement a more natural and idiomatic way to use the API than what we have now.