Simplify importing flatdata-rs

[boxdot]

At the moment, to import flatdata in rust, we need to write:

#[macro_use]
extern crate flatdata

• We should try to remove this requirement.
• Also, nightly compiler fails due to missing flatdata_intersperse macro.

[gferon]

For the second point, see: rust-lang/rust#63888. It's fixed in nightly but not yet in beta.

[VeaaC]

Is this still an issue? @boxdot ?

[boxdot]

Yes, minimal example:

#[macro_use]
extern crate flatdata;

include!(concat!(env!("OUT_DIR"), "/graph.rs"));

fn main() {
    println!("Hello, world!");
}

Looks like there is also a bug in the docs which tell to do:

#![allow(dead_code)]
include!(concat!(env!("OUT_DIR"), "/graph.rs"));

but the dead code annotation actually does not work.