Get rid of PyToken

[ExpHP]

I'm not sure what PyToken is supposed to serve as a proof of, exactly, but in any case, it is possible to own one without a hold on the GIL. The following code segfaults on my machine.

Cargo.toml

[package]
authors = ["Michael Lamparski <diagonaldevice@gmail.com>"]
name = "token"
version = "0.1.0"

[dependencies]
pyo3 = { version = "0.2.3" }

src/main.rs

#![feature(proc_macro, specialization)]

extern crate pyo3;

use pyo3::prelude::*;

#[py::class]
struct Dummy { }

fn main() {

    // Temporarily acquire the GIL and save the token
    let mut evil = None;
    Python::acquire_gil().python().init(|token| {
        evil = Some(token);
        Dummy { }
    }).unwrap();
    let token = evil.unwrap();

    // Use python without acquiring the GIL
    token.py().import("sys").unwrap();
}

[fafhrd91]

yes, I know about this. token is too weak protection, you can easily abuse it.

I was planing to remove it, I don't have much time at the moment.