Unsafe libspnav FFI bindings for Rust

• Use https://github.com/sjkillen/spnav-rust instead
• X11 types have been made opaque
• Thanks to https://medium.com/dwelo-r-d/using-c-libraries-in-rust-13961948c72a

Dependencies

• Requires libspnav

Building

• Requires clang & llvm-dev
• cargo install bindgen
• Run make to rebuild lib/bindings.rs