Upgrade to bindgen 0.59, which has two new abilities: - specify arbitrary #[derive] attributes to attach to generated structs - request explicit padding fields These two features are enough to replace transmute with serde/bincode.
Explain the purpose of of the 'postgres_ffi' module, explain what the PostgreSQL control file is, and some other minor cleanup.
I had copy-pasted these functions to a few other places. Clean that up, move them to a common module, and add some comments.
