move cnf stuff into a separate crate, not just a module

rust/dpll/Cargo.lock

[root]
name = "cnf"
name = "solve"
version = "0.1.0"

rust/dpll/Cargo.toml

[package]
name = "cnf"
name = "solve"
version = "0.1.0"
authors = ["Lucas Stadler <lu@papill0n.org>"]
[[bin]]
name = "cnf"

rust/dpll/src/lib.rs

pub mod cnf;

rust/dpll/src/main.rs

 *
 * You have been warned...
 */
extern crate solve;
use std::io;
use std::io::Read;
mod cnf;
use solve::cnf;
fn main() {
    let input: &mut String = &mut String::new();